[Federal Register Volume 59, Number 208 (Friday, October 28, 1994)]
[Unknown Section]
[Page ]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-26598]


[Federal Register: October 28, 1994]


_______________________________________________________________________

Part II





Department of Health and Human Services





_______________________________________________________________________



Centers for Disease Control and Prevention



_______________________________________________________________________



Guidelines for Preventing the Transmission of Mycobacterium 
Tuberculosis in Health-Care Facilities, 1994; Notice
DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention


Guidelines for Preventing the Transmission of Mycobacterium 
Tuberculosis in Health-Care Facilities, 1994

AGENCY: Centers for Disease Control and Prevention (CDC), Public Health 
Service, HHS.

ACTION: Notice of Final Revisions to the ``Guidelines for Preventing 
the Transmission of Mycobacterium tuberculosis in Health-Care 
Facilities, 1994.''

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SUMMARY: The purpose of this notice is to print the final ``Guidelines 
for Preventing the Transmission of Mycobacterium tuberculosis in 
Health-Care Facilities, 1994,'' and a summary of comments and responses 
to those comments.

EFFECTIVE DATE: October 28, 1994.

ADDRESSES: This document is also being printed in its entirety as a 
Morbidity and Mortality Weekly Report (MMWR), Recommendations and 
Reports. For copies of the MMWR printing, call CDC's Voice Information 
System (VIS) at (404) 639-1819 or write to the Centers for Disease 
Control and Prevention (CDC), Information Services Office, Mailstop E-
06, Atlanta, GA 30333. An electronic version of this document will be 
available via Anonymous FTP from ftp.cdc.gov after November 18. Type 
``Anonymous'' for the user name and your e-mail address for the 
password. Select the pub directory, then the tbdoc subdirectory. 
Retrieve the README file for instructions on document viewing and 
printing.

FOR FURTHER INFORMATION CONTACT: CDC's Voice Information System at 
(404) 639-1819.

SUPPLEMENTARY INFORMATION:

Background

    On October 12, 1993, CDC published ``Draft Guidelines for 
Preventing the Transmission of Tuberculosis in Health-Care Facilities, 
Second Edition,'' in the Federal Register at 58 FR 52810 with a 60-day 
comment period (which was extended to January 13, 1994). More than 2500 
comments were received and reviewed. The following represents a summary 
of all major comments and a response to each. All comments were 
reviewed and considered in developing the final guidelines. Changes 
were also made to increase clarity and readability.

Comments and Responses

Section I. Introduction

Section II. Recommendations

A. Assignment of Responsibility
    No comments received on this section.
B. Risk Assessment, Development of the TB Control Plan, and Periodic 
Reassessment
    Comments: Provide more flexibility in levels of risk to accommodate 
facilities that rarely or never provide services to patients with 
tuberculosis.
    Response: Two new categories--``very low risk'' and ``minimal 
risk''--were added to accommodate such facilities.
    Comments: Rationale for selecting six patients per year in a given 
area as a criterion for risk level seems arbitrarily defined.
    Response: This criterion is based on surveys conducted by CDC in 
conjunction with the American Hospital Association, the Society for 
Health Care Epidemiology of America, and the Association for 
Professionals in Infection Control and Epidemiology. These surveys 
suggest an increased risk of tuberculin skin test conversion in 
employees working in facilities admitting six or more TB patients per 
year.
    Comments: Repeat skin testing at 3-month intervals in high-risk 
settings is too frequent.
    Response: The high-risk setting is essentially an outbreak setting, 
in which there is evidence of transmission of Mycobacterium 
tuberculosis. In this situation, it is reasonable to conduct follow-up 
skin testing 12 weeks (3 months) after the initial testing. If there is 
no evidence of further transmission and any deficiencies in infection 
control practices and facilities have been corrected, the area is no 
longer considered high risk, and there is no need to continue testing 
every 3 months.
    Comments: A cluster of skin test conversions is defined as two or 
more conversions in one area within 3 months; however, because of the 
limitations of skin testing, this may not represent true conversions 
due to nosocomial transmission.
    Response: It is assumed that a cluster would be investigated to 
determine the likelihood that it truly represents nosocomial 
transmission. The situation would be classified as high risk only if 
this evaluation supported a conclusion that nosocomial transmission had 
occurred. The recommendation will be modified to clarify this point.
    Comments: Retesting all employees in a area when a single 
conversion has occurred may not be warranted.
    Response: Clarified wording of this section.
C. Detection of Patients Who Have Active TB
    Comments: Provide more information and place more emphasis on early 
detection, specifically those categories of patients in whom TB should 
be suspected.
    Response: Reemphasized the need for protocols for early detection 
and the need to review and revise these protocols periodically. In 
addition, explained that the index of suspicion varies from place to 
place, depending on various factors, including the prevalence of 
infection in the population served.
    Comments: Increase the recommended turnaround time for stat smears 
for laboratories unable to use rapid methods and remove the term ``stat 
smears'' from recommendations.
    Response: Reemphasized the importance of rapid laboratory results. 
Discouraged batching of specimens and added the recommendation that 
laboratories that perform mycobacterial tests infrequently refer 
specimens to an experienced laboratory. Removed the term ``stat 
smears''.
D. Management of Patients in Ambulatory Care Settings and Emergency 
Rooms
    Comments: Clarify the requirement that patients should wear 
surgical masks but that health care workers (HCWs) must wear 
particulate respirators.
    Response: Added a footnote to explain the rationale for each: one 
to protect the worker from infection and the other to decrease the 
amount of droplet nuclei in the air produced by the patient.
    Comments: Do not require isolation rooms in all ambulatory care 
settings.
    Response: Restated and clarified that if TB patients are seen 
infrequently or not at all in a facility, an isolation room is not 
needed. However, there must be a protocol for referral and periodic 
risk assessment.
E. Management of Hospitalized Patients With TB
    Comments: Do not require isolation for most or all pediatric 
patients.
    Response: Provided some examples of potentially infectious 
pediatric TB patients and added a section explaining the need to 
evaluate parents as possible source of infection.
    Comments: Radiology should not, and in many facilities, cannot have 
a separate area for TB patients.
    Response: Clarified the section to refer only to facilities where 
many TB patients are seen.
    Comments: Provide clearer recommendations for visitors and their 
use of respiratory protection.
    Response: Expanded the recommendations to make clearer.
    Comments: Requiring three negative smears to release a patient from 
isolation is excessive and unnecessary, especially for suspected TB 
cases.
    Response: Clarified: if TB has been ruled out, there is no need to 
retain the patient in isolation. Reiterated that if TB has been 
confirmed the patient should have three consecutive negative sputum 
smears collected on different days.
    Comments: The recommendation that TB patients not be discharged to 
home if an HIV-infected person or young children are in the household 
is potentially problematic.
    Response: Clarified that this is one of many factors that should be 
taken into consideration when planning to discharge TB patients, not a 
hard-and-fast rule.
    Comments: Labeling door TB Isolation would breach patient 
confidentiality.
    Response: Recommended using the term Isolation rather than TB 
Isolation giving hospitals the flexibility to label doors according to 
individual policies or practices.
F. Engineering Controls
Ultraviolet Germicidal Irradiation
    Comments: Data are insufficient to recommend the use of UVGI. 
Greater emphasis should be placed on the use of UVGI in health care 
settings.
    Response: No change. No new information was provided and the 
current guidelines were considered appropriate.
Ventilation
    Comments: Provide specific recommendations on engineering controls 
as they relate to risk level. Provide information on how to evaluate 
air changes per hour (ACHs). There are no data to support requirement 
for six or more ACHs.
    Response: Clarified: 6 ACHs are an absolute minimum, and a level of 
12 or more ACHs are recommended, especially in new construction. 
Referred to table S3-1, which provides the number of air changes per 
hour and the minutes required for removal efficiencies of 90.0%, 99.0%, 
and 99.9%. The 12 ACHs or more recommendation was arrived at by both 
use of this table and NIOSH experimental data. Added discussion on the 
benefits of higher ventilation and recommended ideal performance 
criteria.
    Comments: Provide retrofit information and some examples of 
alternative methods for achieving required ventilation.
    Response: In response to requests for information on alternative 
methods, retrofit information, and interim guidelines, expanded the 
introduction to this section and introduced a clearer hierarchy of 
ventilation methods.
    Comments: Provide clearer directions on bronchoscopy location and 
ventilation requirements.
    Response: The confusion about bronchoscopy location resulted from 
inconsistency in the guidelines in relation to performing the procedure 
in the operating room vs. an area of patient isolation. Clarified this 
point.
Room Units
    Comments: Provide information on room air ``cleaning'' units. Can 
these units serve as a substitute for not having six or more ACHs?
    Response: Revised the document to present more clearly the 
potential use of air cleaning units in areas where air changes are 
limited and to set their place in a control hierarchy. In addition, 
further clarified the importance of placement, performance, and 
potential limitations. Added a statement that manufacturers of these 
units should provide documentation of both the efficiency of the HEPA 
filter and the efficiency of the device in lowering air contaminant 
levels.
Negative Pressure
    Comments: Because smoke can be an irritant, the use of smoke tubes 
for continuous pressure monitoring should be replaced with flutter 
strips. Daily monitoring of negative pressure is unnecessary and labor 
intensive.
    Response: Made no change in the recommended monitoring schedule. 
The concern over the use of smoke tubes is unfounded. Controlled tests 
by NIOSH have shown that the quantity of smoke that is released is so 
minute that it is not measurable in the air. The location of the 
patient and the length of time the patient is exposed dilute the smoke 
to several orders of magnitude below an 8-hour exposure limit. It is 
not practical and often not effective to use flutter strips or 
continuous monitoring devices as alternatives to indicate directional 
air movement. The air flow (due usually to the small clearance area 
under a door) is insufficient to move the flutter strip. Likewise, low 
negative pressure, which will satisfactorily provide adequate 
directional air flow into the isolation room, may not be readable on 
continuous monitoring devices. Devices must be capable of reading 0.001 
inch of water, the established minimum, to be effective. Clarified the 
overall guidance in this area by indicating the use of smoke as the 
optimum test procedure and clearly stating the potential results of 
flutter strips and continuous instrumentation. Used illustrations to 
clarify procedures for setting negative pressure.
HEPA Filtration
    Comments: The recommendations on the use of HEPA filtration in a 
ventilation system are not supported by the data. The purpose of its 
use is unclear.
    Response: Addressed the general confusion on the use of HEPA 
filtration by rewording the section.
    Comments: Provide information on the necessity of ``bag in--bag 
out'' and ``red bag'' use when changing filters.
    Response: Eliminated the bag in--bag out requirement since there is 
no evidence that it is needed. Retained the red bag recommendation 
(treating filters as infectious waste).
G. Respiratory Protection and Supplement 4. Respiratory Protection
    Comments: HEPA filtered masks are too expensive, and no data 
support their use. Instituting a fit-testing program and, in general, a 
respiratory protection program is too expensive. HCWs will not wear the 
masks. The masks are uncomfortable, impede communication, and interfere 
with general patient care.
    Response: Retained the original performance criteria on respiratory 
protection; however, details on specific respirators such as dust-mist 
and dust-fume-mist were removed. Removed the respiratory protection 
table and accompanying performance characteristics in the supplement in 
anticipation of the new certification process. Retained the 
explanations about fit, fit testing and fit checking, and the elements 
of a respiratory protection program. Added a statement about ongoing 
research being conducted on various forms of respiratory protection.
    Comments: The performance criteria for respiratory protection for 
HCWs exposed to tuberculosis fail to take into consideration the 
potential higher level of risk for workers in selected settings (e.g., 
bronchoscopy performed on patients suspected of having TB or autopsy 
performed on deceased persons suspected of having TB at the time of 
death).
    Response: Clarified that the facility's risk assessment may 
identify those limited settings where the estimated risk for 
transmission of M. tuberculosis may be such that a level of respiratory 
protection exceeding the standard criteria is appropriate.
    Comments: NIOSH certification process should be changed to 
accommodate the certification of a more appropriate mask for use in 
health care settings.
    Response: On May 24, 1994, CDC published in the Federal Register 
(59 FR 26850) a Notice of Proposed Rule Making on revised certification 
requirements for respiratory protective devices. The certification of 
air-purifying respirators under these proposed requirements would 
enable respirator users to select from a broader range of certified 
respirators that meet the current performance criteria in this 
document.
    Comments: Provide information on the storage and reuse of 
respirators.
    Response: Expanded the general guidelines on the reuse of 
respirators classified as disposable and those with replaceable 
filters. Retained the original suggestion to refer to manufacturers 
recommendations concerning storage and reuse.
    Comment: It is unclear which facilities must have a respiratory 
protection program.
    Response: Clarified that facilities that do not have isolation 
rooms for TB, that do not perform cough-inducing procedures, and refer 
all potential TB patients need not have a respirator program but must 
perform a periodic risk assessment, have protocols for referral, and an 
infection control plan that is periodically reviewed.
H. Cough-Inducing Procedures
    No comments were received that differed substantively from those 
covered in other sections of the document.
I. Education and Training of Health-Care Workers
    Comments: In general, the comments supported the concept of 
education for HCWs. Persons from a number of specialties noted that 
educational programs should be flexible and should allow for the 
selection of information to be included in these programs and that the 
frequency of training should be based on the risk of TB transmission in 
the facility or area. Some suggested emphasis on educating physicians 
in the early recognition and proper treatment for persons with 
tuberculosis. Because of difficulties with compliance with attendance 
and the time needed away from the job in the busy health care 
environment, concern was expressed about the increasing requirements 
for mandatory annual educational training sessions on various subjects 
(bloodborne pathogens, fire safety, hazardous exposure). A few persons 
suggested that CDC provide standardized training materials. A few 
commented on the expense of the training program, including the 
respirator training program.
    Response: Modified section to allow more flexibility in selection 
of topics to cover and frequency of education.
J. Health Care Worker Counseling, Screening and Evaluation
Counseling
    Comments: Most of the comments on this section were very favorable. 
Some persons commented that the HIV-infected HCW may not report their 
infection to the facility and asked about the facility's responsibility 
to HCWs and to patients should this occur. Some expressed concern about 
confidentiality and about the Americans with Disabilities Act.
    Response: No changes were considered necessary.
Screening HCWs for Active Disease
    Comments: Evaluation of every HCW with a cough of 2 weeks or 
greater duration is excessive.
    Response: Reemphasized the need to tailor each program to fit the 
situation. The infection rate in a particular facility, the time of 
year (e.g., flu season), the potential exposure of individual workers--
all these need to be taken into consideration.
Screening HCWs for Latent TB Infection
    Comments: Annual PPD testing in areas of low prevalence is 
unnecessary. It is unclear which HCWs should be tested. Provide clearer 
information on the number of conversions during a specified period to 
trigger the testing of others from the same area or group.
    Response: Modified this section and coordinated it with 
recommendations in the risk assessment and the skin testing supplement, 
which give clearer guidance on who should be tested and how frequently.
    Comments: Two-step skin testing is not necessary for all HCWs, 
especially those who are transferring from hospitals and whose PPD 
results are negative and those from areas where the prevalence of 
booster phenomenon is low or where boosting was assessed as no problem.
    Response: Clarified that 2-step testing is not necessary if an HCW 
has had a documented negative PPD result in the past 12 months or if 
the institution has determined that boosting is not common in their 
population. Also added the potential consequences of misinterpreting a 
boosted reaction as a new infection.
Evaluation and Management of Health Care Workers With Positive PPD 
Tests
Evaluation
    Comments: M. tuberculosis antimicrobial susceptibilities should be 
recorded in the HCW's medical record and given to the employee if he or 
she leaves the facility. The HCW can then be put on appropriate therapy 
if active disease develops. Persons who are PPD positive and have not 
had adequate preventive therapy should be monitored at least annually.
    Response: Added these recommendations to this section.
Routine and Follow-Up Chest Radiographs
    Comments: Consideration should be given to performing chest 
radiographs on HCWs whose PPD tests are positive.
    Response: Reemphasized the need to monitor more frequently for 
symptoms of TB in high-risk persons but retained the statement that 
regular chest radiographs have not been shown to be effective in 
detecting TB in these persons.
Work Restrictions
    Comments: Requiring three consecutive negative smears before an HCW 
who is receiving treatment for active TB can return to work is 
excessive. A person who has improved does not cough and does not 
produce sputum and may be kept off duty unnecessarily.
    Response: Confusion had been caused by an incorrect wording in the 
guidelines, that ``negative smears on consecutive days'' were required. 
This has been clarified. The recommendation for 3 consecutive negative 
smears collected on separate days was deemed appropriate and retained.
    Comments: If an HCW who has a positive skin test result does not 
take preventive therapy, the HCW should be required to be seen and 
interviewed frequently.
    Response: The frequency of follow-up was not specified to allow for 
flexibility.
Supplement 2
    Comment: HCWs should be allowed to read their own skin test 
results.
    Response: Retained the recommendation that they not read their own 
test results and cited a reference as to why they should not.
    Comment: Clarification is needed on what constitutes a positive 
skin test result for HCWs.
    Response: Added to the recommendation that a HCW may be considered 
positive if the induration is 10 mm or more and referred to the 
Diagnostic Standards (ATS/CDC statement).
K. Problem Evaluation
    Comments and subsequent changes made in the risk assessment section 
also apply here. Revised this section.
L. Coordination With Public Health Department
    No substantive comments or questions received on this section.
M. Additional Considerations for Selected Areas
    Comment: What controls are needed in special areas such as hospices 
and nursing homes?
    Response: Added a statement on the need to conduct a risk 
assessment and have an infection control plan, which should be reviewed 
and revised regularly. For hospices and nursing homes, it was clarified 
that TB isolation rooms are not needed if they do not provide care to 
TB patients. Restated the need for a referral protocol with periodic 
review.
Supplement 5 Decontamination: Cleaning, Disinfecting, and Sterilizing 
of Patient-Care Equipment
    Comments: Only one comment on this section concerned the cleaning 
of ventilation ducts.
    Response: No changes were considered necessary.

Revised Guidelines

    Following are the final guidelines based on analysis of the 
comments described above.

    Dated: October 19, 1994.
Arthur C. Jackson,
Associate Director for Management and Operations, Centers for Disease 
Control and Prevention (CDC).

Guidelines for Preventing the Transmission of Mycobacterium 
Tuberculosis in Health-Care Facilities, 1994

Contents

Executive Summary
I. Introduction
    A. Purpose of Document
    B. Epidemiology, Transmission, and Pathogenesis of TB
    C. Risk for Nosocomial Transmission of M. tuberculosis
    D. Fundamentals of TB Infection Control
II. Recommendations
    A. Assignment of Responsibility
    B. Risk Assessment, Development of the TB Infection-Control 
Plan, and Periodic Reassessment
    1. Risk assessment
    a. General
    b. Community TB profile
    c. Case surveillance
    d. Analysis of HCW PPD test screening data
    e. Review of TB patient medical records
    f. Observation of TB infection-control practices
    g. Engineering evaluation
    2. Development of the TB Infection-Control Plan
    3. Periodic Reassessment
    4. Examples of Risk Assessment
    C. Identifying, Evaluating, and Initiating Treatment for 
Patients Who May Have Active TB
    1. Identifying patients who may have active TB
    2. Diagnostic evaluation for active TB
    3. Initiation of treatment for suspected or confirmed TB
    D. Management of Patients Who May Have Active TB in Ambulatory-
Care Settings and Emergency Departments
    E. Management of Hospitalized Patients Who Have Confirmed or 
Suspected TB
    1. Initiation of isolation for TB
    2. TB isolation practices
    3. The TB isolation room
    4. Discontinuation of TB isolation
    5. Discharge planning
    F. Engineering Control Recommendations
    1. General ventilation
    2. Additional engineering control approaches
    a. HEPA filtration
    b. UVGI
    G. Respiratory Protection
    H. Cough-Inducing and Aerosol-Generating Procedures
    1. General guidelines
    2. Special considerations for bronchoscopy
    3. Special considerations for the administration of aerosolized 
pentamidine
    I. Education and Training of HCWs
    J. HCW Counseling, Screening, and Evaluation
    1. Counseling HCWs regarding TB
    2. Screening HCWs for active TB
    3. Screening HCWs for latent TB infection
    4. Evaluation and management of HCWs who have positive PPD test 
results or active TB
    a. Evaluation
    b. Routine and follow-up chest radiographs
    c. Workplace restrictions
    (1) Active TB
    (2) Latent TB infection
    K. Problem Evaluation
    1. Investigating PPD test conversions and active TB in HCWs
    a. Investigating PPD test conversions in HCWs
    b. Investigating cases of active TB in HCWs
    2. Investigating possible patient-to-patient transmission of M. 
tuberculosis
    3. Investigating contacts of patients and HCWs who have 
infectious TB
    L. Coordination with the Public Health Department
    M. Additional Considerations for Selected Areas in Health-Care 
Facilities and Other Health-Care settings
    1. Selected areas in health-care facilities
    a. Operating rooms
    b. Autopsy rooms
    c. Laboratories
    2. Other health-care settings
    a. Emergency medical services
    b. Hospices
    c. Long-term care facilities
    d. Correctional facilities
    e. Dental settings
    f. Home-health-care settings
    g. Medical offices
Supplement 1: Determining the Infectiousness of a TB Patient
Supplement 2: Diagnosis and Treatment of Latent TB Infection and 
Active TB
I. Diagnostic Procedures for TB Infection and Disease
    A. PPD Skin Testing and Anergy Testing
    1. Application and reading of PPD skin tests
    2. Interpretation of PPD skin tests
    a. General
    b. HCWs
    3. Anergy testing
    4. Pregnancy and PPD skin testing
    5. BCG vaccination and PPD skin testing
    6. The booster phenomenon
    B. Chest Radiography
    C. Bacteriology
II. Preventive Therapy for Latent TB Infection and Treatment of 
Active TB
    A. Preventive Therapy for Latent TB Infection
    B. Treatment of Patients Who Have Active TB
Supplement 3: Engineering Controls
I. Introduction
II. Ventilation
    A. Local Exhaust Ventilation
    1. Enclosing devices
    2. Exterior devices
    3. Discharge exhaust from booths, tents, and hoods
    B. General Ventilation
    1. Dilution and removal
    a. Types of general ventilation systems
    b. Ventilation rates
    2. Airflow patterns within rooms (air mixing)
    3. Airflow direction in the facility
    a. Directional airflow
    b. Negative pressure for achieving directional airflow
    4. Achieving negative pressure in a room
    a. Pressure differential
    b. Alternate methods for achieving negative pressure
    c. Monitoring negative pressure
    C. HEPA filtration
    1. Use of HEPA filtration when exhausting air to the outside
    2. Recirculation of HEPA-filtered air to other areas of a 
facility
    3. Recirculation of HEPA-filtered air within a room
    a. Fixed room-air recirculation systems
    b. Portable room-air recirculation units
    c. Evaluation of room-air recirculation systems and units
    4. Installing, maintaining, and monitoring HEPA filters
    D. TB Isolation Rooms and Treatment Rooms
    1. Preventing the escape of droplet nuclei from the room
    2. Reducing the concentration of droplet nuclei in the room
    3. Exhaust from TB isolation rooms and treatment rooms
    4. Alternatives to TB isolation rooms
III. UVGI
    A. Applications
    1. Duct irradiation
    2. Upper-room air irradiation
    B. Limitations
    C. Safety Issues
    D. Exposure Criteria for UV Radiation
    E. Maintenance and Monitoring
    1. Labelling and posting
    2. Maintenance
    3. Monitoring
Supplement 4: Respiratory Protection
I. Considerations for Selection of Respirators
    A. Performance Criteria for Personal Respirators for Protection 
Against Transmission of M. tuberculosis
    B. Specific Respirators
    C. The Effectiveness of Respiratory Protective Devices
    1. Face-seal leakage
    2. Filter leakage
    3. Fit testing
    4. Fit checking
    5. Reuse of respirators
II. Implementing a Personal Respiratory Protection Program
Supplement 5: Decontamination--Cleaning, Disinfecting, and 
Sterilizing of Patient-Care Equipment
References
Glossary
Index
    List of Tables
    List of Figures

Executive Summary

    This document updates and replaces all previously published 
guidelines for the prevention of Mycobacterium tuberculosis 
transmission in health-care facilities. The purpose of this revision is 
to emphasize the importance of (a) the hierarchy of control measures, 
including administrative and engineering controls and personal 
respiratory protection; (b) the use of risk assessments for developing 
a written tuberculosis (TB) control plan; (c) early identification and 
management of persons who have TB; (d) TB screening programs for 
health-care workers (HCWs); (e) HCW training and education; and (f) the 
evaluation of TB infection-control programs.
    Transmission of M. tuberculosis is a recognized risk to patients 
and HCWs in health-care facilities. Transmission is most likely to 
occur from patients who have unrecognized pulmonary or laryngeal TB, 
are not on effective anti-TB therapy, and have not been placed in TB 
isolation. Several recent TB outbreaks in health-care facilities, 
including outbreaks of multidrug-resistant TB, have heightened concern 
about nosocomial transmission. Patients who have multidrug-resistant TB 
can remain infectious for prolonged periods, which increases the risk 
for nosocomial and/or occupational transmission of M. tuberculosis. 
Increases in the incidence of TB have been observed in some geographic 
areas; these increases are related partially to the high risk for TB 
among immunosuppressed persons, particularly those infected with human 
immunodeficiency virus (HIV). Transmission of M. tuberculosis to HIV-
infected persons is of particular concern because these persons are at 
high risk for developing active TB if they become infected with the 
bacteria. Thus, health-care facilities should be particularly alert to 
the need for preventing transmission of M. tuberculosis in settings in 
which HIV-infected persons work or receive care.
    Supervisory responsibility for the TB infection-control program 
should be assigned to a designated person or group of persons who 
should be given the authority to implement and enforce TB infection-
control policies. An effective TB infection-control program requires 
early identification, isolation, and treatment of persons who have 
active TB. The primary emphasis of TB infection-control plans in 
health-care facilities should be achieving these three goals by the 
application of a hierarchy of control measures, including (a) the use 
of administrative measures to reduce the risk for exposure to persons 
who have infectious TB, (b) the use of engineering controls to prevent 
the spread and reduce the concentration of infectious droplet nuclei, 
and (c) the use of personal respiratory protective equipment in areas 
where there is still a risk for exposure to M. tuberculosis (e.g., TB 
isolation rooms). Implementation of a TB infection-control program 
requires risk assessment and development of a TB infection-control 
plan; early identification, treatment, and isolation of infectious TB 
patients; effective engineering controls; an appropriate respiratory 
protection program; HCW TB training, education, counseling, and 
screening; and evaluation of the program's effectiveness.
    Although completely eliminating the risk for transmission of M. 
tuberculosis in all health-care facilities may not be possible at the 
present time, adherence to these guidelines should reduce the risk to 
persons in these settings. Recently, nosocomial TB outbreaks have 
demonstrated the substantial morbidity and mortality among patients and 
HCWs that have been associated with incomplete implementation of CDC's 
Guidelines for Preventing the Transmission of Tuberculosis in Health-
Care Facilities, with Special Focus on HIV-Related Issues published in 
1990.* Follow-up investigations at some of these hospitals have 
documented that complete implementation of measures similar or 
identical to those in the 1990 TB Guidelines significantly reduced or 
eliminated nosocomial transmission of M. tuberculosis to patients and/
or HCWs.
---------------------------------------------------------------------------

    *CDC. Guidelines for Preventing the Transmission of Tuberculosis 
in Health-Care Facilities, with Special Focus on HIV-Related Issues. 
MMWR 1990; 39 (No. RR-17).
---------------------------------------------------------------------------

I. Introduction

A. Purpose of Document
    In April 1992, the National MDR-TB Task Force published the 
National Action Plan to Combat Multidrug-Resistant Tuberculosis (1). 
The publication was a response to reported nosocomial outbreaks of 
tuberculosis (TB), including outbreaks of multidrug-resistant TB (MDR-
TB), and the increasing incidence of TB in some geographic areas. The 
plan called for the update and revision of the guidelines for 
preventing nosocomial transmission of Mycobacterium tuberculosis 
published December 7, 1990 (2).
    Public meetings were held in October 1992 and January 1993 to 
discuss revision of the 1990 TB Guidelines (2). CDC received 
considerable input on various aspects of infection control, including 
health-care worker (HCW) education; administrative controls (e.g., 
having protocols for the early identification and management of 
patients who have TB); the need for more specific recommendations 
regarding ventilation; and clarification on the use of respiratory 
protection in health-care settings. On the basis of these events and 
the input received, on October 12, 1993, CDC published in the Federal 
Register the Draft Guidelines For Preventing the Transmission of 
Tuberculosis in Health-Care Facilities, Second Edition (3). During and 
after the 90-day comment period following publication of this draft, 
CDC's TB Infection-Control Guidelines Work Group received and reviewed 
more than 2,500 comments.
    The purpose of this document is to make recommendations for 
reducing the risk for transmitting M. tuberculosis to HCWs, patients, 
volunteers, visitors, and other persons in these settings. The 
information also may serve as a useful resource for educating HCWs 
about TB.
    These recommendations update and replace all previously published 
CDC recommendations for TB infection control in health-care facilities 
(2, 4). The recommendations in this document are applicable primarily 
to inpatient facilities in which health care is provided (e.g., 
hospitals, medical wards in correctional facilities, nursing homes, and 
hospices). Recommendations applicable to ambulatory-care facilities, 
emergency departments, home-health-care settings, emergency medical 
services, medical offices, dental settings, and other facilities or 
residential settings that provide medical care are provided in separate 
sections, with cross-references to other sections of the guidelines if 
appropriate.
    Designated personnel at health-care facilities should conduct a 
risk assessment for the entire facility and for each area* and 
occupational group, determine the risk for nosocomial or occupational 
transmission of M. tuberculosis, and implement an appropriate TB 
infection-control program. The extent of the TB infection-control 
program may range from a simple program emphasizing administrative 
controls in settings where there is minimal risk for exposure to M. 
tuberculosis, to a comprehensive program that includes administrative 
controls, engineering controls, and respiratory protection in settings 
where the risk for exposure is high. In all settings, administrative 
measures should be used to minimize the number of HCWs exposed to M. 
tuberculosis while still providing optimal care for TB patients. HCWs 
providing care to patients who have TB should be informed about the 
level of risk for transmission of M. tuberculosis and the appropriate 
control measures to minimize that risk.
---------------------------------------------------------------------------

    *Area: a structural unit (e.g., a hospital ward or laboratory) 
or functional unit (e.g., an internal medicine service) in which 
HCWs provide services to and share air with a specific patient 
population or work with clinical specimens that may contain viable 
M. tuberculosis organisms. The risk for exposure to M. tuberculosis 
in a given area depends on the prevalence of TB in the population 
served and the characteristics of the environment.
---------------------------------------------------------------------------

    In this document, the term ``HCWs'' refers to all the paid and 
unpaid persons working in health-care settings who have the potential 
for exposure to M. tuberculosis. This may include, but is not limited 
to, physicians; nurses; aides; dental workers; technicians; workers in 
laboratories and morgues; emergency medical service (EMS) personnel; 
students; part-time personnel; temporary staff not employed by the 
health-care facility; and persons not involved directly in patient care 
but who are potentially at risk for occupational exposure to M. 
tuberculosis (e.g., volunteer workers and dietary, housekeeping, 
maintenance, clerical, and janitorial staff).
    Although the purpose of this document is to make recommendations 
for reducing the risk for transmission of M. tuberculosis in health-
care facilities, the process of implementing these recommendations must 
safeguard, in accordance with applicable state and federal laws, the 
confidentiality and civil rights of persons who have TB.
B. Epidemiology, Transmission, and Pathogenesis of TB
    The prevalence of TB is not distributed evenly throughout all 
segments of the U.S. population. Some subgroups or persons have a 
higher risk for TB either because they are more likely than other 
persons in the general population to have been exposed to and infected 
with M. tuberculosis or because their infection is more likely to 
progress to active TB after they have been infected (5). In some cases, 
both of these factors may be present. Groups of persons known to have a 
higher prevalence of TB infection include contacts of persons who have 
active TB, foreign-born persons from areas of the world with a high 
prevalence of TB (e.g., Asia, Africa, the Caribbean, and Latin 
America), medically underserved populations (e.g., some African-
Americans, Hispanics, Asians and Pacific Islanders, American Indians, 
and Alaskan Natives), homeless persons, current or former correctional-
facility inmates, alcoholics, injecting-drug users, and the elderly. 
Groups with a higher risk for progression from latent TB infection to 
active disease include persons who have been infected recently (i.e., 
within the previous 2 years), children less than <4 years of age, 
persons with fibrotic lesions on chest radiographs, and persons with 
certain medical conditions (i.e., human immunodeficiency virus [HIV] 
infection, silicosis, gastrectomy or jejuno-ileal bypass, being 
10% below ideal body weight, chronic renal failure with 
renal dialysis, diabetes mellitus, immunosuppression resulting from 
receipt of high-dose corticosteroid or other immunosuppressive therapy, 
and some malignancies) (5).
    M. tuberculosis is carried in airborne particles, or droplet 
nuclei, that can be generated when persons who have pulmonary or 
laryngeal TB sneeze, cough, speak, or sing (6). The particles are an 
estimated 1-5 m in size, and normal air currents can keep them 
airborne for prolonged time periods and spread them throughout a room 
or building (7). Infection occurs when a susceptible person inhales 
droplet nuclei containing M. tuberculosis, and these droplet nuclei 
traverse the mouth or nasal passages, upper respiratory tract, and 
bronchi to reach the alveoli of the lungs. Once in the alveoli, the 
organisms are taken up by alveolar macrophages and spread throughout 
the body. Usually within 2-10 weeks after initial infection with M. 
tuberculosis, the immune response limits further multiplication and 
spread of the tubercle bacilli; however, some of the bacilli remain 
dormant and viable for many years. This condition is referred to as 
latent TB infection. Persons with latent TB infection usually have 
positive purified protein derivative (PPD)-tuberculin skin-test 
results, but they do not have symptoms of active TB, and they are not 
infectious.
    In general, persons who become infected with M. tuberculosis have 
approximately a 10% risk for developing active TB during their 
lifetimes. This risk is greatest during the first 2 years after 
infection. Immunocompromised persons have a greater risk for the 
progression of latent TB infection to active TB disease; HIV infection 
is the strongest known risk factor for this progression. Persons with 
latent TB infection who become coinfected with HIV have approximately 
an 8%-10% risk per year for developing active TB (8). HIV-infected 
persons who are already severely immunosuppressed and who become newly 
infected with M. tuberculosis have an even greater risk for developing 
active TB (9-12).
    The probability that a person who is exposed to M. tuberculosis 
will become infected depends primarily on the concentration of 
infectious droplet nuclei in the air and the duration of exposure. 
Characteristics of the TB patient that enhance transmission include (a) 
disease in the lungs, airways, or larynx; (b) presence of cough or 
other forceful expiratory measures; (c) presence of acid-fast bacilli 
(AFB) in the sputum; (d) failure of the patient to cover the mouth and 
nose when coughing or sneezing; (e) presence of cavitation on chest 
radiograph; (f) inappropriate or short duration of chemotherapy; and 
(g) administration of procedures that can induce coughing or cause 
aerosolization of M. tuberculosis (e.g., sputum induction). 
Environmental factors that enhance the likelihood of transmission 
include (a) exposure in relatively small, enclosed spaces; (b) 
inadequate local or general ventilation that results in insufficient 
dilution and/or removal of infectious droplet nuclei; and (c) 
recirculation of air containing infectious droplet nuclei. 
Characteristics of the persons exposed to M. tuberculosis that may 
affect the risk for becoming infected are not as well defined. In 
general, persons who have been infected previously with M. tuberculosis 
may be less susceptible to subsequent infection. However, reinfection 
can occur among previously infected persons, especially if they are 
severely immunocompromised. Vaccination with Bacille of Calmette and 
Guerin (BCG) probably does not affect the risk for infection; rather, 
it decreases the risk for progressing from latent TB infection to 
active TB (13). Finally, although it is well established that HIV 
infection increases the likelihood of progressing from latent TB 
infection to active TB, it is unknown whether HIV infection increases 
the risk for becoming infected if exposed to M. tuberculosis.
C. Risk for Nosocomial Transmission of M. Tuberclosis
    Transmission of M. tuberclosis is a recognized risk in health-care 
facilities (14-22). The magnitude of the risk varies considerably by 
the type of health-care facility, the prevalence of TB in the 
community, the patient population served, the HCW's occupational group, 
the area of the health-care facility in which the HCW works, and the 
effectiveness of TB infection-control interventions. The risk may be 
higher in areas where patients with TB are provided care before 
diagnosis and initiation of TB treatment and isolation precautions 
(e.g., in clinic waiting areas and emergency departments) or where 
diagnostic or treatment procedures that stimulate coughing are 
performed. Nosocomial transmission of M. tuberclosis has been 
associated with close contact with persons who have infectious TB and 
with the performance of certain procedures (e.g., bronchoscopy [17], 
endotracheal intubation and suctioning [18], open abscess irrigation 
[20], and autopsy [21,22]). Sputum induction and aerosol treatments 
that induce coughing may also increase the potential for transmission 
of M. tuberclosis (23,24). Personnel of health-care facilities should 
be particularly alert to the need for preventing transmission of M. 
tuberclosis in those facilities in which immunocompromised persons 
(e.g., HIV-infected persons) work or receive care--especially if cough-
inducing procedures, such as sputum induction and aerosolized 
pentamidine treatments, are being performed.
    Several TB outbreaks among persons in health-care facilities have 
been reported recently (11,24-28; CDC, unpublished data). Many of these 
outbreaks involved transmission of multidrug-resistant strains of M. 
tuberclosis to both patients and HCWs. Most of the patients and some of 
the HCWs were HIV-infected persons in whom new infection progressed 
rapidly to active disease. Mortality associated with those outbreaks 
was high (range: 43%-93%). Furthermore, the interval between diagnosis 
and death was brief (range of median intervals: 4-16 weeks). Factors 
contributing to these outbreaks included delayed diagnosis of TB, 
delayed recognition of drug resistance, and delayed initiation of 
effective therapy--all of which resulted in prolonged infectiousness, 
delayed initiation and inadequate duration of TB isolation, inadequate 
ventilation in TB isolation rooms, lapses in TB isolation practices and 
inadequate precautions for cough-inducing procedures, and lack of 
adequate respiratory protection. Analysis of data collected from three 
of the health-care facilities involved in the outbreaks indicates that 
transmission of M. tuberclosis decreased significantly or ceased 
entirely in areas where measures similar to those in the 1990 TB 
Guidelines were implemented (2,29-32). However, several interventions 
were implemented simultaneously, and the effectiveness of the separate 
interventions could not be determined.
D. Fundamentals of TB Infection Control
    An effective TB infection-control program requires early 
identification, isolation, and effective treatment of persons who have 
active TB. The primary emphasis of the TB infection-control plan should 
be on achieving these three goals. In all health-care facilities, 
particularly those in which persons who are at high risk for TB work or 
receive care, policies and procedures for TB control should be 
developed, reviewed periodically, and evaluated for effectiveness to 
determine the actions necessary to minimize the risk for transmission 
of M. tuberclosis.
    The TB infection-control program should be based on a hierarchy of 
control measures. The first level of the hierarchy, and that which 
affects the largest number of persons, is using administrative measures 
intended primarily to reduce the risk for exposing uninfected persons 
to persons who have infectious TB. These measures include (a) 
developing and implementing effective written policies and protocols to 
ensure the rapid identification, isolation, diagnostic evaluation, and 
treatment of persons likely to have TB; (b) implementing effective work 
practices among HCWs in the health-care facility (e.g., correctly 
wearing respiratory protection and keeping doors to isolation rooms 
closed); (c) educating, training, and counseling HCWs about TB; and (d) 
screening HCWs for TB infection and disease.
    The second level of the hierarchy is the use of engineering 
controls to prevent the spread and reduce the concentration of 
infectious droplet nuclei. These controls include (a) direct source 
control using local exhaust ventilation, (b) controlling direction of 
airflow to prevent contamination of air in areas adjacent to the 
infectious source, (c) diluting and removing contaminated air via 
general ventilation, and (d) air cleaning via air filtration or 
ultraviolet germicidal irradiation (UVGI).
    The first two levels of the hierarchy minimize the number of areas 
in the health-care facility where exposure to infectious TB may occur, 
and they reduce, but do not eliminate, the risk in those few areas 
where exposure to M. tuberculosis can still occur (e.g., rooms in which 
patients with known or suspected infectious TB are being isolated and 
treatment rooms in which cough-inducing or aerosol-generating 
procedures are performed on such patients). Because persons entering 
such rooms may be exposed to M. tuberculosis, the third level of the 
hierarchy is the use of personal respiratory protective equipment in 
these and certain other situations in which the risk for infection with 
M. tuberculosis may be relatively higher.
    Specific measures to reduce the risk for transmission of M. 
tuberculosis include the following:
     Assigning to specific persons in the health-care facility 
the supervisory responsibility for designing, implementing, evaluating, 
and maintaining the TB infection-control program (Section II.A).
     Conducting a risk assessment to evaluate the risk for 
transmission of M. tuberculosis in all areas of the health-care 
facility, developing a written TB infection-control program based on 
the risk assessment, and periodically repeating the risk assessment to 
evaluate the effectiveness of the TB infection-control program (Section 
II.B).
     Developing, implementing, and enforcing policies and 
protocols to ensure early identification, diagnostic evaluation, and 
effective treatment of patients who may have infectious TB (Section 
II.C; Suppl. 2).
     Providing prompt triage for and appropriate management of 
patients in the outpatient setting who may have infectious TB (Section 
II.D).
     Promptly initiating and maintaining TB isolation for 
persons who may have infectious TB and who are admitted to the 
inpatient setting (Section II.E; Suppl. 1).
     Effectively planning arrangements for discharge (Section 
II.E).
     Developing, installing, maintaining, and evaluating 
ventilation and other engineering controls to reduce the potential for 
airborne exposure to M. tuberculosis (Section II.F; Suppl. 3).
     Developing, implementing, maintaining, and evaluating a 
respiratory protection program (Section II.G; Suppl. 4).
     Using precautions while performing cough-inducing 
procedures (Section II.H; Suppl. 3).
     Educating and training HCWs about TB, effective methods 
for preventing transmission of M. tuberculosis, and the benefits of 
medical screening programs (Section II.I).
     Developing and implementing a program for routine periodic 
counseling and screening of HCWs for active TB and latent TB infection 
(Section II.J; Suppl. 2).
     Promptly evaluating possible episodes of M. tuberculosis 
transmission in health-care facilities, including PPD skin-test 
conversions among HCWs, epidemiologically associated cases among HCWs 
or patients, and contacts of patients or HCWs who have TB and who were 
not promptly identified and isolated (Section II.K).
     Coordinating activities with the local public health 
department, emphasizing reporting, and ensuring adequate discharge 
follow-up and the continuation and completion of therapy (Section 
II.L).

II. Recommendations

A. Assignment of Responsibility
     Supervisory responsibility for the TB infection-control 
program should be assigned to a designated person or group of persons 
with expertise in infection control, occupational health, and 
engineering. These persons should be given the authority to implement 
and enforce TB infection-control policies.
     If supervisory responsibility is assigned to a committee, 
one person should be designated as the TB contact person. Questions and 
problems can then be addressed to this person.
B. Risk Assessment, Development of the TB Infection-Control Plan, and 
Periodic Reassessment
1. Risk Assessment
    a. General.
     TB infection-control measures for each health-care 
facility should be based on a careful assessment of the risk for 
transmission of M. tuberculosis in that particular setting. The first 
step in developing the TB infection-control program should be to 
conduct a baseline risk assessment to evaluate the risk for 
transmission of M. tuberculosis in each area and occupational group in 
the facility (Table 1, Figure 1). Appropriate infection-control 
interventions can then be developed on the basis of actual risk. Risk 
assessments should be performed for all inpatient and outpatient 
settings (e.g., medical and dental offices).
     Regardless of risk level, the management of patients with 
known or suspected infectious TB should not vary. However, the index of 
suspicion for infectious TB among patients, the frequency of HCW PPD 
skin testing, the number of TB isolation rooms, and other factors will 
depend on whether the risk for transmission of M. tuberculosis in the 
facility, area, or occupational group is high, intermediate, low, very 
low, or minimal.
     The risk assessment should be conducted by a qualified 
person or group of persons (e.g., hospital epidemiologists, infectious 
disease specialists, pulmonary disease specialists, infection-control 
practitioners, health-care administrators, occupational health 
personnel, engineers, HCWs, or local public health personnel).
     The risk assessment should be conducted for the entire 
facility and for specific areas within the facility (e.g., medical, TB, 
pulmonary, or HIV wards; HIV, infectious disease, or pulmonary clinics; 
and emergency departments or other areas where TB patients might 
receive care or where cough-inducing procedures are performed). This 
should include both inpatient and outpatient areas. In addition, risk 
assessments should be conducted for groups of HCWs who work throughout 
the facility rather than in a specific area (e.g., respiratory 
therapists; bronchoscopists; environmental services, dietary, and 
maintenance personnel; and students, interns, residents, and fellows).
     Classification of risk for a facility, for a specific 
area, and for a specific occupational group should be based on (a) the 
profile of TB in the community; (b) the number of infectious TB 
patients admitted to the area or ward, or the estimated number of 
infectious TB patients to whom HCWs in an occupational group may be 
exposed; and (c) the results of analysis of HCW PPD test conversions 
(where applicable) and possible person-to-person transmission of M. 
tuberculosis (Figure 1).
     All TB infection-control programs should include periodic 
reassessments of risk. The frequency of repeat risk assessments should 
be based on the results of the most recent risk assessment (Table 2, 
Figure 1).
     The ``minimal-risk'' category applies only to an entire 
facility. A ``minimal-risk'' facility does not admit TB patients to 
inpatient or outpatient areas and is not located in a community with TB 
(i.e., counties or communities in which TB cases have not been reported 
during the previous year). Thus, there is essentially no risk for 
exposure to TB patients in the facility. This category may also apply 
to many outpatient settings (e.g., many medical and dental offices).

Table 1. Elements of a Risk Assessment for Tuberculosis (TB) in Health-
care Facilities

    1. Review the community TB profile (from public health department 
data).
    2. Review the number of TB patients who were treated in each area 
of the facility (both inpatient and outpatient). (This information can 
be obtained by analyzing laboratory surveillance data and by reviewing 
discharge diagnoses or medical and infection-control records.)
    3. Review the drug-susceptibility patterns of TB isolates of 
patients who were treated at the facility.
    4. Analyze purified protein derivative (PPD)-tuberculin skin-test 
results of health-care workers (HCWs), by area or by occupational group 
for HCWs not assigned to specific area (e.g., respiratory therapists).
    5. To evaluate infection-control parameters, review medical records 
of a sample of TB patients seen at the facility.

Calculate Intervals From

     Admission until TB suspected;
     Admission until TB evaluation performed;
     Admission until acid-fast bacilli (AFB) specimens ordered;
     AFB specimens ordered until AFB specimens collected;
     AFB specimens collected until AFB smears performed and 
reported;
     AFB specimens collected until cultures performed and 
reported;
     AFB specimens collected until species identification 
conducted and reported;
     AFB specimens collected until drug-susceptibility tests 
performed and reported;
     Admission until TB isolation initiated;
     Admission until TB treatment initiated; and
     Duration of TB isolation.

Obtain the Following Additional Information

     Were appropriate criteria used for discontinuing 
isolation?
     Did the patient have a history of prior admission to the 
facility?
     Was the TB treatment regimen adequate?
     Were follow-up sputum specimens collected properly?
     Was appropriate discharge planning conducted?
    6. Perform an observational review of TB infection control 
practices.
    7. Review the most recent environmental evaluation and maintenance 
procedures.

BILLING CODE 4163-18-P
      

TN28OC94.000


TN28OC94.001


BILLING CODE 4163-18-C

                                           Table 2.--Elements of a Tuberculosis (TB) Infection-Control Program                                          
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                 Risk categories                                        
                        Element                         ------------------------------------------------------------------------------------------------
                                                            Minimal       Very low          Low             Intermediate                  High          
--------------------------------------------------------------------------------------------------------------------------------------------------------
Assigning responsibility (Section II.A)                                                                                                                 
    Designated TB control officer or committee.........  R              R              R              R.......................  R                       
Conducting a risk assessment (Section II.B.1)                                                                                                           
    Baseline risk assessment...........................  R              R              R              R.......................  R                       
    Community TB profile: incidence, prevalence, and     Y              Y              Y              Y.......................  Y                       
     drug-susceptibility patterns.                                                                                                                      
    Facility case surveillance (laboratory- and          C              C              C              C.......................  C                       
     discharge-diagnosis-based).                                                                                                                        
    Analysis of purified protein derivative (PPD) test   N/A            V*             Y              Every 6-12 mos..........  Every 3 mos.            
     results among health-care workers (HCWs).                                                                                                          
    Review of TB patient medical records...............  N/A            O      Y              Every 6-12 mos..........  Every 3 mos.            
    Observation of infection-control practices.........  N/A            N/A            Y              Every 6-12 mos..........  Every 3 mos.            
    Evaluation of engineering control maintenance......  OSec.          OSec.          Y              Every 6-12 mos..........  Every 3 mos.            
Developing a TB infection control plan (Section II.B.2)                                                                                                 
    Written TB infection control plan..................  R              R              R              R.......................  R                       
Periodically reassessing risk (Section II.B.3)                                                                                                          
    Reassessment of risk...............................  Y              Y              Y              Every 6-12 mos..........  Every 3 mos.            
Identifying, evaluating, and initiating treatment for                                                                                                   
 patients who may have active TB (Section II.C)                                                                                                         
    Protocol (clinical prediction rules for             R              R              R              R.......................  R                       
     identifying patients who may have active TB.                                                                                                       
    Protocol for diagnostic evaluation of patients who   N/A            R              R              R.......................  R                       
     may have active TB**.                                                                                                                              
    Protocol for reporting laboratory results to         N/A            R              R              R.......................  R                       
     clinicians, infection-control practitioners,                                                                                                       
     collaborating referral facilities, and appropriate                                                                                                 
     health department(s).                                                                                                                              
    Protocol for initiating treatment of patients who    N/A            R              R              R.......................  R                       
     may have active TB**.                                                                                                                              
Managing patients who may have TB in ambulatory-care                                                                                                    
 settings and emergency departments (Section II.D)                                                                                                      
    Triage system for identifying patients who have      R              R              R              R.......................  R                       
     active TB in emergency departments and ambulatory-                                                                                                 
     care settings.                                                                                                                                     
    Protocol for managing patients who may have active   R              R              R              R.......................  R                       
     TB in emergency departments and ambulatory-care                                                                                                    
     settings.                                                                                                                                          
    Protocol for referring patients who may have active  R              R              N/A.....  N/A     
     TB to collaborating facility.                                                      a                                                               
Managing hospitalized patients who may have TB (Section                                                                                                 
 II.E)                                                                                                                                                  
    Appropriate number of TB isolation roomsN/ASecs. ..  N/A            N/A            R              R.......................  R                       
    Protocol for initiating TB isolation...............  N/A            N/A            R              R.......................  R                       
    Protocol for TB isolation practices................  N/A            N/A            R              R.......................  R                       
    Protocol for discontinuing TB isolation............  N/A            N/A            R              R.......................  R                       
    Protocol for discharge planning....................  N/A            N/A            R              R.......................  R                       
Engineering controls (Suppl. 3, Section II.F)                                                                                                           
    Protocol(s) for maintenance of engineering controls  OSec.          OSec.          R              R.......................  R                       
Respiratory protection (Suppl. 4, Section II.G)                                                                                                         
    Respiratory protection program.....................  N/A            V*             R              R.......................  R                       
Cough-inducing and aerosol-generating procedures                                                                                                        
 (Section II.H)                                                                                                                                         
    Protocol(s) for performing cough-inducing or         O              O            R              R.......................  R                       
     aerosol-generating procedures.                                                                                                                     
    Engineering controls for performing cough-inducing   OSec.          O            R              R.......................  R                       
     or aerosol-generating procedures.                                                                                                                  
Educating and Training HCWs (Section II.I)                                                                                                              
    Educating and training HCWs regarding TB...........  R              R              R              R.......................  R                       
Counseling and screening HCWs (Section II.J)                                                                                                            
    Counseling HCWs regarding TB.......................  R              R              R              R.......................  R                       
    Protocol for identifying and evaluating HCWs who     R              R              R              R.......................  R                       
     have signs or symptoms of active TB.                                                                                                               
    Baseline PPD testing of HCWs.......................  O***           R              R              R.......................  R                       
    Routine periodic PPD screening of HCWs for latent    N/A            V*             Y              Every 6-12 mos..........  Every 3 mos.            
     TB infection.                                                                                                                                      
    Protocol for evaluating and managing HCWs who have   R              R              R              R.......................  R                       
     positive PPD tests.                                                                                                                                
    Protocol for managing HCWs who have active TB......  R              R              R              R.......................  R                       
Conducting a problem evaluation (Section II.K)                                                                                                          
    Protocol for investigating PPD conversions and       R              R              R              R.......................  R                       
     active TB in HCWs.                                                                                                                                 
    Protocol for investigating possible patient-to-      R              R              R              R.......................  R                       
     patient transmission of Mycobacterium tuberculosis.                                                                                                
    Protocol for investigating possible contacts of TB   R              R              R              R.......................  R                       
     patients who were not diagnosed initially as                                                                                                       
     having TB and were not placed in isolation.                                                                                                        
Coordination with the public health department (Section                                                                                                 
 II.L)                                                                                                                                                  
    Effective system for reporting patients who have     R              R              R              R.......................  R                       
     suspected or confirmed TB to appropriate health                                                                                                    
     department(s).                                                                                                                                     
--------------------------------------------------------------------------------------------------------------------------------------------------------
R=recommended; Y=yearly; C=continual; N/A=not applicable; O=optional; V=variable.                                                                       
                                                                                                                                                        
*Because very low-risk facilities do not admit patients who may have active TB to inpatient areas, most HCWs in such facilities do not need routine     
  follow-up PPD screening after baseline PPD testing is done. However, those who are involved in the initial assessment and diagnostic evaluation of    
  patients in the ambulatory-care, emergency, and admitting departments of such facilities or in the outpatient management of patients with active TB   
  could be exposed potentially to a patient who has active TB. These HCWs may need to receive routine periodic PPD screening. Similarly, these HCWs may 
  need to be included in a respiratory protection program.                                                                                              
Because very low-risk facilities do not admit patients suspected of having active TB, review of TB patient medical records is not applicable.   
  However, follow-up of patients who were identified during triage as possibly having active TB and referred to another institution for further         
  evaluation and management may be useful in evaluating the effectiveness of the triage system.                                                         
Sec. Some minimal or very low-risk facilities may elect to use engineering controls (e.g., booths for cough-inducing procedures, portable high-         
  efficiency particulate [HEPA] filtration units, ultraviolet germicidal irradiation units) in triage/waiting areas. In such situations, appropriate    
  protocols for maintaining this equipment should be in place, and this maintenance should be evaluated periodically.                                   
The criteria used in clinical prediction rules will probably vary from facility to facility depending on the prevalence of TB in the population served 
  by the facility and on the clinical, radiographic, and laboratory characteristics of TB patients examined in the facility.                            
**The protocols should be consistent with CDC/American Thoracic Society recommendations (33).                                                           
Protocols for referring patients who require specialized treatment (e.g., patients with multidrug-resistant TB) may be appropriate.     
Secs. Based on maximum daily number of patients requiring TB isolation for suspected or confirmed active TB. Isolation rooms should meet the performance
  criteria specified in these guidelines.                                                                                                               
If such procedures are used in the triage protocol(s) for identifying patients who may have active TB.                                                
***Minimal-risk facilities do not need to maintain an ongoing PPD skin-testing program. However, baseline PPD testing of HCWs may be advisable so that  
  if an unexpected exposure does occur, conversions can be distinguished from positive PPD test results caused by previous exposures.                   

     The ``very low-risk'' category generally applies only to 
an entire facility. A very low-risk facility is one in which (a) 
patients with active TB are not admitted to inpatient areas but may 
receive initial assessment and diagnostic evaluation or outpatient 
management in outpatient areas (e.g., ambulatory-care and emergency 
departments) and (b) patients who may have active TB and need inpatient 
care are promptly referred to a collaborating facility. In such 
facilities, the outpatient areas in which exposure to patients with 
active TB could occur should be assessed and assigned to the 
appropriate low-, intermediate-, or high-risk category. Categorical 
assignment will depend on the number of TB patients examined in the 
area during the preceding year and whether there is evidence of 
nosocomial transmission of M. tuberculosis in the area. If TB cases 
have been reported in the community, but no patients with active TB 
have been examined in the outpatient area during the preceding year, 
the area can be designated as very low risk (e.g., many medical 
offices).
    The referring and receiving facilities should establish a referral 
agreement to prevent inappropriate management and potential loss to 
follow-up of patients suspected of having TB during evaluation in the 
triage system of a very low-risk facility.
    In some facilities in which TB patients are admitted to inpatient 
areas, a very low-risk protocol may be appropriate for areas (e.g., 
administrative areas) or occupational groups that have only a very 
remote possibility of exposure to M. tuberculosis.
    The very low-risk category may also be appropriate for outpatient 
facilities that do not provide initial assessment of persons who may 
have TB, but do screen patients for active TB as part of a limited 
medical screening before undertaking specialty care (e.g., dental 
settings).
     ``Low-risk'' areas or occupational groups are those in 
which (a) the PPD test conversion rate is not greater than that for 
areas or groups in which occupational exposure to M. tuberculosis is 
unlikely or than previous conversion rates for the same area or group, 
(b) no clusters* of PPD test conversions have occurred, (c) person-to-
person transmission of M. tuberculosis has not been detected, and (d) 
fewer than six TB patients are examined or treated per year.
---------------------------------------------------------------------------

    *Cluster: two or more PPD skin-test conversions occurring within 
a 3-month period among HCWs in a specific area or occupational 
group, and epidemiologic evidence suggests occupational (nosocomial) 
transmission.
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     ``Intermediate-risk'' areas or occupational groups are 
those in which (a) the PPD test conversion rate is not greater than 
that for areas or groups in which occupational exposure to M. 
tuberculosis is unlikely or than previous conversion rates for the same 
area or group, (b) no clusters of PPD test conversions have occurred, 
(c) person-to-person transmission of M. tuberculosis) has not been 
detected, and (d) six or more patients with active TB are examined or 
treated each year. Survey data suggest that facilities in which six or 
more TB patients are examined or treated each year may have an 
increased risk for transmission of M. tuberculosis (CDC, unpublished 
data); thus, areas in which six or more patients with active TB are 
examined or treated each year (or occupational groups in which HCWs are 
likely to be exposed to six or more TB patients per year) should be 
classified as ``intermediate risk.''
     ``High-risk'' areas or occupational groups are those in 
which (a) the PPD test conversion rate is significantly greater than 
for areas or groups in which occupational exposure to M. tuberculosis 
is unlikely or than previous conversion rates for the same area or 
group, and epidemiologic evaluation suggests nosocomial transmission; 
or (b) a cluster of PPD test conversions has occurred, and 
epidemiologic evaluation suggests nosocomial transmission of M. 
tuberculosis; or (c) possible person-to-person transmission of M. 
tuberculosis has been detected.
     If no data or insufficient data for adequate determination 
of risk have been collected, such data should be compiled, analyzed, 
and reviewed expeditiously.
    b. Community TB profile.
     A profile of TB in the community that is served by the 
facility should be obtained from the public health department. This 
profile should include, at a minimum, the incidence (and prevalence, if 
available) of active TB in the community and the drug-susceptibility 
patterns of M. tuberculosis isolates (i.e., the antituberculous agents 
to which each isolate is susceptible and those to which it is 
resistant) from patients in the community.
    c. Case surveillance.
     Data concerning the number of suspected and confirmed 
active TB cases among patients and HCWs in the facility should be 
systematically collected, reviewed, and used to estimate the number of 
TB isolation rooms needed, to recognize possible clusters of nosocomial 
transmission, and to assess the level of potential occupational risk. 
The number of TB patients in specific areas of a facility can be 
obtained from laboratory surveillance data on specimens positive for 
AFB smears or M. tuberculosis cultures, from infection-control records, 
and from databases containing information about hospital discharge 
diagnoses.
     Drug-susceptibility patterns of M. tuberculosis isolates 
from TB patients treated in the facility should be reviewed to identify 
the frequency and patterns of drug resistance. This information may 
indicate a need to modify the initial treatment regimen or may suggest 
possible nosocomial transmission or increased occupational risk.
    d. Analysis of HCW PPD test screening data.
     Results of HCW PPD testing should be recorded in the 
individual HCW's employee health record and in a retrievable aggregate 
database of all HCW PPD test results. Personal identifying information 
should be handled confidentially. PPD test conversion rates should be 
calculated at appropriate intervals to estimate the risk for PPD test 
conversions for each area of the facility and for each specific 
occupational group not assigned to a specific area (Table 2). To 
calculate PPD test conversion rates, the total number of previously 
PPD-negative HCWs tested in each area or group (i.e., the denominator) 
and the number of PPD test conversions among HCWs in each area or group 
(the numerator) must be obtained.
     PPD test conversion rates for each area or occupational 
group should be compared with rates for areas or groups in which 
occupational exposure to M. tuberculosis is unlikely and with previous 
conversion rates in the same area or group to identify areas or groups 
where the risk for occupational PPD test conversions may be increased. 
A low number of HCWs in a specific area may result in a greatly 
increased rate of conversion for that area, although the actual risk 
may not be significantly greater than that for other areas. Testing for 
statistical significance (e.g., Fisher's exact test or chi square test) 
may assist interpretation; however, lack of statistical significance 
may not rule out a problem (i.e., if the number of HCWs tested is low, 
there may not be adequate statistical power to detect a significant 
difference). Thus, interpretation of individual situations is 
necessary.
     An epidemiologic investigation to evaluate the likelihood 
of nosocomial transmission should be conducted if PPD test conversions 
are noted (Section II.K.1).
     The frequency and comprehensiveness of the HCW PPD testing 
program should be evaluated periodically to ensure that all HCWs who 
should be included in the program are being tested at appropriate 
intervals. For surveillance purposes, earlier detection of transmission 
may be enhanced if HCWs in a given area or occupational group are 
tested on different scheduled dates rather than all being tested on the 
same date (Section II.J.3).
    e. Review of TB patient medical records.
     The medical records of a sample of TB patients examined at 
the facility can be reviewed periodically to evaluate infection-control 
parameters (Table 1). Parameters to examine may include the intervals 
from date of admission until (a) TB was suspected, (b) specimens for 
AFB smears were ordered, (c) these specimens were collected, (d) tests 
were performed, and (e) results were reported. Moreover, the adequacy 
of the TB treatment regimens that were used should be evaluated.
     Medical record reviews should note previous hospital 
admissions of TB patients before the onset of TB symptoms. Patient-to-
patient transmission may be suspected if active TB occurs in a patient 
who had a prior hospitalization during which exposure to another TB 
patient occurred or if isolates from two or more TB patients have 
identical characteristic drug-susceptibility or DNA fingerprint 
patterns.
     Data from the case review should be used to determine if 
there is a need to modify (a) protocols for identifying and isolating 
patients who may have infectious TB, (b) laboratory procedures, (c) 
administrative policies and practices, or (d) protocols for patient 
management.
    f. Observation of TB infection-control practices.
     Assessing adherence to the policies of the TB infection-
control program should be part of the evaluation process. This 
assessment should be performed on a regular basis and whenever an 
increase occurs in the number of TB patients or HCW PPD test 
conversions. Areas at high risk for transmission of M. tuberculosis 
should be monitored more frequently than other areas. The review of 
patient medical records provides information on HCW adherence to some 
of the policies of the TB infection-control program. In addition, work 
practices related to TB isolation (e.g., keeping doors to isolation 
rooms closed) should be observed to determine if employers are 
enforcing, and HCWs are adhering to, these policies and if patient 
adherence is being enforced. If these policies are not being enforced 
or adhered to, appropriate education and other corrective action should 
be implemented.
    g. Engineering evaluation
     Results of engineering maintenance measures should be 
reviewed at regular intervals (Table 3). Data from the most recent 
evaluation and from maintenance procedures and logs should be reviewed 
carefully as part of the risk assessment.
2. Development of the TB Infection-Control Plan
     Based on the results of the risk assessment, a written TB 
infection-control plan should be developed and implemented for each 
area of the facility and for each occupational group of HCWs not 
assigned to a specific area of the facility (Table 2; Table 3).
     The occurrence of drug-resistant TB in the facility or the 
community, or a relatively high prevalence of HIV infection among 
patients or HCWs in the community, may increase the concern about 
transmission of M. tuberculosis and may influence the decision 
regarding which protocol to follow (i.e., a higher-risk classification 
may be selected).
     Health-care facilities are likely to have a combination of 
low-, intermediate-, and high-risk areas or occupational groups during 
the same time period. The appropriate protocol should be implemented 
for each area or group.
     Areas in which cough-inducing procedures are performed on 
patients who may have active TB should, at the minimum, implement the 
intermediate-risk protocol.
3. Periodic Reassessment
     Follow-up risk assessment should be performed at the 
interval indicated by the most recent risk assessment (Figure 1; Table 
2). Based on the results of the follow-up assessment, problem 
evaluation may need to be conducted or the protocol may need to be 
modified to a higher- or lower-risk level.

Table 3. Characteristics of an Effective Tuberculosis (TB) Infection-
Control Program*

I. Assignment of responsibility
---------------------------------------------------------------------------

    *A program such as this is appropriate for health-care 
facilities in which there is a high risk for transmission of 
Mycobacterium tuberculosis.
---------------------------------------------------------------------------

    A. Assign responsibility for the TB infection-control program to 
qualified person(s).
    B. Ensure that persons with expertise in infection control, 
occupational health, and engineering are identified and included.
II. Risk assessment, TB infection-control plan, and periodic 
reassessment
    A. Initial risk assessments
    1. Obtain information concerning TB in the community.
    2. Evaluate data concerning TB patients in the facility.
    3. Evaluate data concerning purified protein derivative (PPD)-
tuberculin skin-test conversions among health-care workers (HCWs) in 
the facility.
    4. Rule out evidence of person-to-person transmission.
    B. Written TB infection-control program
    1. Select initial risk protocol(s).
    2. Develop written TB infection-control protocols.
    C. Repeat risk assessment at appropriate intervals.
    1. Review current community and facility surveillance data and PPD-
tuberculin skin-test results.
    2. Review records of TB patients.
    3. Observe HCW infection-control practices.
    4. Evaluate maintenance of engineering controls.
III. Identification, evaluation, and treatment of patients who have TB
    A. Screen patients for signs and symptoms of active TB:
    1. On initial encounter in emergency department or ambulatory-care 
setting.
    2. Before or at the time of admission.
    B. Perform radiologic and bacteriologic evaluation of patients who 
have signs and symptoms suggestive of TB.
    C. Promptly initiate treatment.
IV. Managing outpatients who have possible infectious TB
    A. Promptly initiate TB precautions.
    B. Place patients in separate waiting areas or TB isolation rooms.
    C. Give patients a surgical mask, a box of tissues, and 
instructions regarding the use of these items.
V. Managing inpatients who have possible infectious TB
    A. Promptly isolate patients who have suspected or known infectious 
TB.
    B. Monitor the response to treatment.
    C. Follow appropriate criteria for discontinuing isolation.
VI. Engineering recommendations
    A. Design local exhaust and general ventilation in collaboration 
with persons who have expertise in ventilation engineering.
    B. Use a single-pass air system or air recirculation after high-
efficiency particulate air (HEPA) filtration in areas where infectious 
TB patients receive care.
    C. Use additional measures, if needed, in areas where TB patients 
may receive care.
    D. Design TB isolation rooms in health-care facilities to achieve 
6 air changes per hour (ACH) for existing facilities and 
12 ACH for new or renovated facilities.
    E. Regularly monitor and maintain engineering controls.
    F. TB isolation rooms that are being used should be monitored daily 
to ensure they maintain negative pressure relative to the hallway and 
all surrounding areas.
    G. Exhaust TB isolation room air to outside or, if absolutely 
unavoidable, recirculate after HEPA filtration.
VII. Respiratory protection
    A. Respiratory protective devices should meet recommended 
performance criteria.
    B. Respiratory protection should be used by persons entering rooms 
in which patients with known or suspected infectious TB are being 
isolated, by HCWs when performing cough-inducing or aerosol-generating 
procedures on such patients, and by persons in other settings where 
administrative and engineering controls are not likely to protect them 
from inhaling infectious airborne droplet nuclei.
    C. A respiratory protection program is required at all facilities 
in which respiratory protection is used.
VIII. Cough-inducing procedures
    A. Do not perform such procedures on TB patients unless absolutely 
necessary.
    B. Perform such procedures in areas that have local exhaust 
ventilation devices (e.g., booths or special enclosures) or, if this is 
not feasible, in a room that meets the ventilation requirements for TB 
isolation.
    C. After completion of procedures, TB patients should remain in the 
booth or special enclosure until their coughing subsidies.
IX. HCW TB training and education
    A. All HCWs should receive periodic TB education appropriate for 
their work responsibilities and duties.
    B. Training should include the epidemiology of TB in the facility.
    C. TB education should emphasize concepts of the pathogenesis of 
and occupational risk for TB.
    D. Training should describe work practices that reduce the 
likelihood of transmitting M. tuberculosis.
X. HCW counseling and screening
    A. Counsel all HCWs regarding TB and TB infection.
    B. Counsel all HCWs about the increased risk to immunocompromised 
persons for developing active TB.
    C. Perform PPD skin tests on HCWs at the beginning of their 
employment, and repeat PPD tests at periodic intervals.
    D. Evaluate symptomatic HCWs for active TB.
XI. Evaluate HCW PPD test conversions and possible nosocomial 
transmission of M. tuberculosis.
XII. Coordinate efforts with public health department(s)
     After each risk assessment, the staff responsible for TB 
control, in conjunction with other appropriate HCWs, should review all 
TB control policies to ensure that they are effective and meet current 
needs.
4. Examples of Risk Assessment
    Examples of six hypothetical situations and the means by which 
surveillance data are used to select a TB control protocol are 
described as follows:
    Hospital A. The overall HCW PPD test conversion rate in the 
facility is 1.6%. No areas or HCW occupational groups have a 
significantly greater PPD test conversion rate than areas or groups in 
which occupational exposure to M. tuberculosis is unlikely (or than 
previous rates for the same area or group). No clusters of PPD test 
conversions have occurred. Patient-to-patient transmission has not been 
detected. Patients who have TB are admitted to the facility, but no 
area admits six or more TB patients per year. The low-risk protocol 
will be followed in all areas.
    Hospital B. The overall HCW PPD test conversion rate in the 
facility is 1.8%. The PPD test conversion rate for the medical 
intensive-care unit rate is significantly higher than all other areas 
in the facility. The problem identification process is initiated 
(Section II.K). It is determined that all TB patients have been 
isolated appropriately. Other potential problems are then evaluated, 
and the cause for the higher rate is not identified. After consulting 
the public health department TB infection-control program, the high-
risk protocol is followed in the unit until the PPD test conversion 
rate is similar to areas of the facility in which occupational exposure 
to TB patients is unlikely. If the rate remains significantly higher 
than other areas, further evaluation, including environmental and 
procedural studies, will be performed to identify possible reasons for 
the high conversion rate.
    Hospital C. The overall HCW PPD test conversion rate in the 
facility is 2.4%. Rates range from 0 to 2.6% for the individual areas 
and occupational groups. None of these rates is significantly higher 
than rates for areas in which occupational exposure to M. tuberculosis 
is unlikely. No particular HCW group has higher conversion rates than 
the other groups. No clusters of HCW PPD test conversions have 
occurred. In two of the areas, HCWs cared for more than six TB patients 
during the preceding year. These two areas will follow the 
intermediate-risk protocol, and all other areas will follow the low-
risk protocol. This hospital is located in the southeastern United 
States, and these conversion rates may reflect cross-reactivity with 
nontuberculous mycobacteria.
    Hospital D. The overall HCW PPD test conversion rate in the 
facility is 1.2%. In no area did HCWs care for six or more TB patients 
during the preceding year. Three of the 20 respiratory therapists 
tested had PPD conversions, for a rate of 15%. The respiratory 
therapists who had PPD test conversions had spent all or part of their 
time in the pulmonary function laboratory, where induced sputum 
specimens were obtained. A low-risk protocol is maintained for all 
areas and occupational groups in the facility except for respiratory 
therapists. A problem evaluation is conducted in the pulmonary function 
laboratory (Section II.K). It is determined that the ventilation in 
this area is inadequate. Booths are installed for sputum induction. PPD 
testing and the risk assessment are repeated 3 months later. If the 
repeat testing at 3 months indicates that no more conversions have 
occurred, the respiratory therapists will return to the low-risk 
protocol.
    Hospital E. Hospital E is located in a community that has a 
relatively low incidence of TB. To optimize TB services in the 
community, the four hospitals in the community have developed an 
agreement that one of them (e.g., Hospital G) will provide all 
inpatient services to persons who have suspected or confirmed TB. The 
other hospitals have implemented protocols in their ambulatory-care 
clinics and emergency departments to identify patients who may have 
active TB. These patients are then transferred to Hospital G for 
inpatient care if such care is considered necessary. After discharge 
from Hospital G, they receive follow-up care in the public health 
department's TB clinic. During the preceding year, Hospital E has 
identified fewer than six TB patients in its ambulatory-care and 
emergency departments and has had no PPD test conversions or other 
evidence of M. tuberculosis transmission among HCWs or patients in 
these areas. These areas are classified as low risk, and all other 
areas are classified as very low risk.
    Hospital F. Hospital F is located in a county in which no TB cases 
have been reported during the preceding 2 years. A risk assessment 
conducted at the facility did not identify any patients who had 
suspected or confirmed TB during the preceding year. The facility is 
classified as minimal risk.
C. Identifying, Evaluating, and Initiating Treatment for Patients Who 
May Have Active TB
    The most important factors in preventing transmission of M. 
tuberculosis are the early identification of patients who may have 
infectious TB, prompt implementation of TB precautions for such 
patients, and prompt initiation of effective treatment for those who 
are likely to have TB.
1. Identifying Patients Who May Have Active TB
     Health-care personnel who are assigned responsibility for 
TB infection control in ambulatory-care and inpatient settings should 
develop, implement, and enforce protocols for the early identification 
of patients who may have infectious TB.
     The criteria used in these protocols should be based on 
the prevalence and characteristics of TB in the population served by 
the specific facility. These protocols should be evaluated periodically 
and revised according to the results of the evaluation. Review of 
medical records of patients who were examined in the facility and 
diagnosed as having TB may serve as a guide for developing or revising 
these protocols.
     A diagnosis of TB may be considered for any patient who 
has a persistent cough (i.e., a cough lasting for 3 weeks) 
or other signs or symptoms compatible with active TB (e.g., bloody 
sputum, night sweats, weight loss, anorexia, or fever). However, the 
index of suspicion for TB will vary in different geographic areas and 
will depend on the prevalence of TB and other characteristics of the 
population served by the facility. The index of suspicion for TB should 
be very high in geographic areas or among groups of patients in which 
the prevalence of TB is high (Section I.B). Appropriate diagnostic 
measures should be conducted and TB precautions implemented for 
patients in whom active TB is suspected.
2. Diagnostic Evaluation for Active TB
     Diagnostic measures for identifying TB should be conducted 
for patients in whom active TB is being considered. These measures 
include obtaining a medical history and performing a physical 
examination, PPD skin test, chest radiograph, and microscopic 
examination and culture of sputum or other appropriate specimens 
(6,34,35). Other diagnostic procedures (e.g., bronchoscopy or biopsy) 
may be indicated for some patients (36,37).
     Prompt laboratory results are crucial to the proper 
treatment of the TB patient and to early initiation of infection 
control. To ensure timely results, laboratories performing 
mycobacteriologic tests should be proficient at both the laboratory and 
administrative aspects of specimen processing. Laboratories should use 
the most rapid methods available (e.g., fluorescent microscopy for AFB 
smears; radiometric culture methods for isolation of mycobacteria; 
-nitro--acetylamino--hydroxy-proprophenone 
[NAP] test, nucleic acid probes, or high-pressure liquid chromatography 
[HPLC] for species identification; and radiometric methods for drug-
susceptibility testing). As other more rapid or sensitive tests become 
available, practical, and affordable, such tests should be incorporated 
promptly into the mycobacteriology laboratory. Laboratories that rarely 
receive specimens for mycobacteriologic analysis should refer the 
specimens to a laboratory that more frequently performs these tests.
     Results of AFB sputum smears should be available within 24 
hours of specimen collection (38).
     The probability of TB is greater among patients who have 
positive PPD test results or a history of positive PPD test results, 
who have previously had TB or have been exposed to M. tuberculosis, or 
who belong to a group at high risk for TB (Section I.B). Active TB is 
strongly suggested if the diagnostic evaluation reveals AFB in sputum, 
a chest radiograph suggestive of TB, or symptoms highly suggestive of 
TB. TB can occur simultaneously in immunosuppressed persons who have 
pulmonary infections caused by other organisms (e.g., Pneumocystis 
carinii or Mycobacterium avium complex) and should be considered in the 
diagnostic evaluation of all patients who have symptoms compatible with 
TB (Suppl. 1; Suppl. 2).
     TB may be more difficult to diagnose among persons who 
have HIV infection (or other conditions associated with severe 
suppression of cell-mediated immunity) because of a nonclassical 
clinical or radiographic presentation and/or the simultaneous 
occurrence of other pulmonary infections (e.g., P. carinii pneumonia 
and M. avium complex). The difficulty in diagnosing TB in HIV-infected 
persons may be further compounded by impaired responses to PPD skin 
tests (39,40), the possibly lower sensitivity of sputum smears for 
detecting AFB (41), or the overgrowth of cultures with M. avium complex 
in specimens from patients infected with both M. avium complex and M. 
tuberculosis (42).
     Immunosuppressed patients who have pulmonary signs or 
symptoms that are ascribed initially to infections or conditions other 
than TB should be evaluated initially for coexisting TB. The evaluation 
for TB should be repeated if the patient does not respond to 
appropriate therapy for the presumed cause(s) of the pulmonary 
abnormalities (Suppl. 1; Suppl. 2).
     Patients with suspected or confirmed TB should be reported 
immediately to the appropriate public health department so that 
standard procedures for identifying and evaluating TB contacts can be 
initiated.
3. Initiation of Treatment for Suspected or Confirmed TB
     Patients who have confirmed active TB or who are 
considered highly likely to have active TB should be started promptly 
on appropriate treatment in accordance with current guidelines (Suppl. 
2) (43). In geographic areas or facilities that have a high prevalence 
of MDR-TB, the initial regimen used may need to be enhanced while the 
results of drug-susceptibility tests are pending. The decision should 
be based on analysis of surveillance data.
     While the patient is in the health-care facility, anti-TB 
drugs should be administered by directly observed therapy (DOT), the 
process by which an HCW observes the patient swallowing the 
medications. Continuing DOT after the patient is discharged should be 
strongly considered. This decision and the arrangements for providing 
outpatient DOT should be made in collaboration with the public health 
department.
D. Management of Patients Who May Have Active TB in Ambulatory-Care 
Settings and Emergency Departments
     Triage of patients in ambulatory-care settings and 
emergency departments should include vigorous efforts to promptly 
identify patients who have active TB. HCWs who are the first points of 
contact in facilities that serve populations at risk for TB should be 
trained to ask questions that will facilitate identification of 
patients with signs and symptoms suggestive of TB.
     Patients with signs or symptoms suggestive of TB should be 
evaluated promptly to minimize the amount of time they are in 
ambulatory-care areas. TB precautions should be followed while the 
diagnostic evaluation is being conducted for these patients.
     TB precautions in the ambulatory-care setting should 
include (a) placing these patients in a separate area apart from other 
patients, and not in open waiting areas (ideally, in a room or 
enclosure meeting TB isolation requirements); (b) giving these patients 
surgical masks* to wear and instructing them to keep their masks on; 
and (c) giving these patients tissues and instructing them to cover 
their mouths and noses with the tissues when coughing or sneezing.
---------------------------------------------------------------------------

    *Surgical masks are designed to prevent the respiratory 
secretions of the person wearing the mask from entering the air. 
When not in a TB isolation room, patients suspected of having TB 
should wear surgical masks to reduce the expulsion of droplet nuclei 
into the air. These patients do not need to wear particulate 
respirators, which are designed to filter the air before it is 
inhaled by the person wearing the mask. Patients suspected of having 
or known to have TB should never wear a respirator that has an 
exhalation valve, because the device would provide no barrier to the 
expulsion of droplet nuclei into the air.
---------------------------------------------------------------------------

     TB precautions should be followed for patients who are 
known to have active TB and who have not completed therapy until a 
determination has been made that they are noninfectious (Suppl. 1).
     Patients with active TB who need to attend a health-care 
clinic should have appointments scheduled to avoid exposing HIV-
infected or otherwise severely immunocompromised persons to M. 
tuberculosis. This recommendation could be accomplished by designating 
certain times of the day for appointments for these patients or by 
treating them in areas where immunocompromised persons are not treated.
     Ventilation in ambulatory-care areas where patients at 
high risk for TB are treated should be designed and maintained to 
reduce the risk for transmission of M. tuberculosis. General-use areas 
(e.g., waiting rooms) and special areas (e.g., treatment or TB 
isolation rooms in ambulatory areas) should be ventilated in the same 
manner as described for similar inpatient areas (Sections II.E.3, II.F; 
Suppl. 3). Enhanced general ventilation or the use of air-disinfection 
techniques (e.g., UVGI or recirculation of air within the room through 
high-efficiency particulate air [HEPA] filters) may be useful in 
general-use areas of facilities where many infectious TB patients 
receive care (Section II.F; Suppl. 3).
     Ideally, ambulatory-care settings in which patients with 
TB are frequently examined or treated should have a TB isolation 
room(s) available. Such rooms are not necessary in ambulatory-care 
settings in which patients who have confirmed or suspected TB are seen 
infrequently. However, these facilities should have a written protocol 
for early identification of patients with TB symptoms and referral to 
an area or a collaborating facility where the patient can be evaluated 
and managed appropriately. These protocols should be reviewed on a 
regular basis and revised as necessary. The additional guidelines in 
Section II.H should be followed in ambulatory-care settings where 
cough-inducing procedures are performed on patients who may have active 
TB.
E. Management of Hospitalized Patients Who Have Confirmed or Suspected 
TB
1. Initiation of Isolation for TB
     In hospitals and other inpatient facilities, any patient 
suspected of having or known to have infectious TB should be placed in 
a TB isolation room that has currently recommended ventilation 
characteristics (Section II.E.3; Suppl. 3). Written policies for 
initiating isolation should specify (a) the indications for isolation, 
(b) the person(s) authorized to initiate and discontinue isolation, (c) 
the isolation practices to follow, (d) the monitoring of isolation, (e) 
the management of patients who do not adhere to isolation practices, 
and (f) the criteria for discontinuing isolation.
     In rare circumstances, placing more than one TB patient 
together in the same room may be acceptable. This practice is sometimes 
referred to as ``cohorting.'' Because of the risk for patients becoming 
superinfected with drug-resistant organisms, patients with TB should be 
placed in the same room only if all patients involved (a) have culture-
confirmed TB, (b) have drug-susceptibility test results available on a 
current specimen obtained during the present hospitalization, (c) have 
identical drug-susceptibility patterns on these specimens, and (d) are 
on effective therapy. Having isolates with identical DNA fingerprint 
patterns is not adequate evidence for placing two TB patients together 
in the same room, because isolates with the same DNA fingerprint 
pattern can have different drug-susceptibility patterns.
     Pediatric patients with suspected or confirmed TB should 
be evaluated for potential infectiousness according to the same 
criteria as are adults (i.e., on the basis of symptoms, sputum AFB 
smears, radiologic findings, and other criteria) (Suppl. 1). Children 
who may be infectious should be placed in isolation until they are 
determined to be noninfectious. Pediatric patients who may be 
infectious include those who have laryngeal or extensive pulmonary 
involvement, pronounced cough, positive sputum AFB smears, or cavitary 
TB or those for whom cough-inducing procedures are performed (44).
     The source of infection for a child with TB is often a 
member of the child's family (45). Therefore, parents and other 
visitors of all pediatric TB patients should be evaluated for TB as 
soon as possible. Until they have been evaluated, or the source case is 
identified, they should wear surgical masks when in areas of the 
facility outside of the child's room, and they should refrain from 
visiting common areas in the facility (e.g., the cafeteria or lounge 
areas).
     TB patients in intensive-care units should be treated the 
same as patients in noncritical-care settings. They should be placed in 
TB isolation and have respiratory secretions submitted for AFB smear 
and culture if they have undiagnosed pulmonary symptoms suggestive of 
TB.
     If readmitted to a health-care facility, patients who are 
known to have active TB and who have not completed therapy should have 
TB precautions applied until a determination has been made that they 
are noninfectious (Suppl. 1).
2. TB Isolation Practices
     Patients who are placed in TB isolation should be educated 
about the mechanisms of M. tuberculosis transmission and the reasons 
for their being placed in isolation. They should be taught to cover 
their mouths and noses with a tissue when coughing or sneezing, even 
while in the isolation room, to contain liquid drops and droplets 
before they are expelled into the air (46).
     Efforts should be made to facilitate patient adherence to 
isolation measures (e.g., staying in the TB isolation room). Such 
efforts might include the use of incentives (e.g., providing them with 
telephones, televisions, or radios in their rooms or allowing special 
dietary requests). Efforts should also be made to address other 
problems that could interfere with adherence to isolation (e.g., 
management of the patient's withdrawal from addictive substances 
[including tobacco]).
     Patients placed in isolation should remain in their 
isolation rooms with the door closed. If possible, diagnostic and 
treatment procedures should be performed in the isolation rooms to 
avoid transporting patients through other areas of the facility. If 
patients who may have infectious TB must be transported outside their 
isolation rooms for medically essential procedures that cannot be 
performed in the isolation rooms, they should wear surgical masks that 
cover their mouths and noses during transport. Persons transporting the 
patients do not need to wear respiratory protection outside the TB 
isolation rooms. Procedures for these patients should be scheduled at 
times when they can be performed rapidly and when waiting areas are 
less crowded.
     Treatment and procedure rooms in which patients who have 
infectious TB or who have an undiagnosed pulmonary disease and are at 
high risk for active TB receive care should meet the ventilation 
recommendations for isolation rooms (Section II.E.3; Suppl. 3). 
Ideally, facilities in which TB patients are frequently treated should 
have an area in the radiology department that is ventilated separately 
for TB patients. If this is not possible, TB patients should wear 
surgical masks and should stay in the radiology suite the minimum 
amount of time possible, then be returned promptly to their isolation 
rooms.
     The number of persons entering an isolation room should be 
minimal. All persons who enter an isolation room should wear 
respiratory protection (Section II.G; Suppl. 4). The patient's visitors 
should be given respirators to wear while in the isolation room, and 
they should be given general instructions on how to use their 
respirators.
     Disposable items contaminated with respiratory secretions 
are not associated with transmission of M. tuberculosis. However, for 
general infection-control purposes, these items should be handled and 
transported in a manner that reduces the risk for transmitting other 
microorganisms to patients, HCWs, and visitors and that decreases 
environmental contamination in the health-care facility. Such items 
should be disposed of in accordance with hospital policy and applicable 
regulations (Suppl. 5).
3. The TB Isolation Room
     TB isolation rooms should be single-patient rooms with 
special ventilation characteristics appropriate for the purposes of 
isolation (Suppl. 3). The primary purposes of TB isolation rooms are to 
(a) separate patients who are likely to have infectious TB from other 
persons; (b) provide an environment that will allow reduction of the 
concentration of droplet nuclei through various engineering methods; 
and (c) prevent the escape of droplet nuclei from the TB isolation room 
and treatment room, thus preventing entry of M. tuberculosis into the 
corridor and other areas of the facility.
     To prevent the escape of droplet nuclei, the TB isolation 
room should be maintained under negative pressure (Suppl. 3). Doors to 
isolation rooms should be kept closed, except when patients or 
personnel must enter or exit the room, so that negative pressure can be 
maintained.
     Negative pressure in the room should be monitored daily 
while the room is being used for TB isolation.
     The American Society of Heating, Refrigerating and Air-
Conditioning Engineers, Inc. (ASHRAE) (47), the American Institute of 
Architects (AIA) (48), and the Health Resources and Services 
Administration (49) recommend a minimum of 6 air changes per hour (ACH) 
for TB isolation and treatment rooms. This ventilation rate is based on 
comfort and odor control considerations. The effectiveness of this 
level of airflow in reducing the concentration of droplet nuclei in the 
room, thus reducing the transmission of airborne pathogens, has not 
been evaluated directly or adequately.
    Ventilation rates of >6 ACH are likely to produce an incrementally 
greater reduction in the concentration of bacteria in a room than are 
lower rates (50-52). However, accurate quantitation of decreases in 
risk that would result from specific increases in general ventilation 
levels has not been performed and may not be possible.
    For the purposes of reducing the concentration of droplet nuclei, 
TB isolation and treatment rooms in existing health-care facilities 
should have an airflow of 6 ACH. Where feasible, this 
airflow rate should be increased to 12 ACH by adjusting or 
modifying the ventilation system or by using auxiliary means (e.g., 
recirculation of air through fixed HEPA filtration systems or portable 
air cleaners) (Suppl. 3, Section II.B.5.a) (53). New construction or 
renovation of existing health-care facilities should be designed so 
that TB isolation rooms achieve an airflow of 12 ACH.
     Air from TB isolation rooms and treatment rooms used to 
treat patients who have known or suspected infectious TB should be 
exhausted to the outside in accordance with applicable federal, state, 
and local regulations. The air should not be recirculated into the 
general ventilation. In some instances, recirculation of air into the 
general ventilation system from such rooms is unavoidable (i.e., in 
existing facilities in which the ventilation system or facility 
configuration makes venting the exhaust to the outside impossible). In 
such cases, HEPA filters should be installed in the exhaust duct 
leading from the room to the general ventilation system to remove 
infectious organisms and particulates the size of droplet nuclei from 
the air before it is returned to the general ventilation system 
(Section II.F; Suppl. 3). Air from TB isolation and treatment rooms in 
new or renovated facilities should not be recirculated into the general 
ventilation system.
     Although not required, an anteroom may increase the 
effectiveness of the isolation room by minimizing the potential escape 
of droplet nuclei into the corridor when the door is opened. To work 
effectively, the anteroom should have positive air pressure in relation 
to the isolation room. The pressure relationship between the anteroom 
and the corridor may vary according to ventilation design.
     Upper-room air UVGI may be used as an adjunct to general 
ventilation in the isolation room (Section II.F; Suppl. 3). Air in the 
isolation room may be recirculated within the room through HEPA filters 
or UVGI devices to increase the effective ACH and to increase thermal 
efficiency.
     Health-care facilities should have enough isolation rooms 
to appropriately isolate all patients who have suspected or confirmed 
active TB. This number should be estimated using the results of the 
risk assessment of the health-care facility. Except for minimal-and 
very low-risk health-care facilities, all acute-care inpatient 
facilities should have at least one TB isolation room (Section II.B).
     Grouping isolation rooms together in one area of the 
facility may reduce the possibility of transmitting M. tuberculosis to 
other patients and may facilitate care of TB patients and the 
installation and maintenance of optimal engineering (particularly 
ventilation) controls.
4. Discontinuation of TB Isolation
     TB isolation can be discontinued if the diagnosis of TB is 
ruled out. For some patients, TB can be ruled out when another 
diagnosis is confirmed. If a diagnosis of TB cannot be ruled out, the 
patient should remain in isolation until a determination has been made 
that the patient is noninfectious. However, patients can be discharged 
from the health-care facility while still potentially infectious if 
appropriate postdischarge arrangements can be ensured (Section II.E.5).
     The length of time required for a TB patient to become 
noninfectious after starting anti-TB therapy varies considerably 
(Suppl. 1). Isolation should be discontinued only when the patient is 
on effective therapy, is improving clinically, and has had three 
consecutive negative sputum AFB smears collected on different days.
     Hospitalized patients who have active TB should be 
monitored for relapse by having sputum AFB smears examined regularly 
(e.g., every 2 weeks). Nonadherence to therapy (i.e., failure to take 
medications as prescribed) and the presence of drug-resistant organisms 
are the two most common reasons why patients remain infectious despite 
treatment. These reasons should be considered if a patient does not 
respond clinically to therapy within 2-3 weeks.
     Continued isolation throughout the hospitalization should 
be strongly considered for patients who have MDR-TB because of the 
tendency for treatment failure or relapse (i.e., difficulty in 
maintaining noninfectiousness) that has been observed in such cases.
5. Discharge Planning
     Before a TB patient is discharged from the health-care 
facility, the facility's staff and public health authorities should 
collaborate to ensure continuation of therapy. Discharge planning in 
the health-care facility should include, at a minimum, (a) a confirmed 
outpatient appointment with the provider who will manage the patient 
until the patient is cured, (b) sufficient medication to take until the 
outpatient appointment, and (c) placement into case management (e.g., 
DOT) or outreach programs of the public health department. These plans 
should be initiated and in place before the patient's discharge.
     Patients who may be infectious at the time of discharge 
should only be discharged to facilities that have isolation capability 
or to their homes. Plans for discharging a patient who will return home 
must consider whether all the household members were infected 
previously and whether any uninfected household members are at very 
high risk for active TB if infected (e.g., children <4 years of age or 
persons infected with HIV or otherwise severely immunocompromised). If 
the household does include such persons, arrangements should be made to 
prevent them from being exposed to the TB patient until a determination 
has been made that the patient is noninfectious.
F. Engineering Control Recommendations
1. General Ventilation
    This section deals only with engineering controls for general-use 
areas of health-care facilities (e.g., waiting-room areas and emergency 
departments). Recommendations for engineering controls for specific 
areas of the facility (e.g., TB isolation rooms) are contained in the 
sections encompassing those areas. Details regarding ventilation 
design, evaluation, and supplemental approaches are described in 
Supplement 3.
     Health-care facilities should either (a) include as part 
of their staff an engineer or other professional with expertise in 
ventilation or (b) have this expertise available from a consultant who 
is an expert in ventilation engineering and who also has hospital 
experience. These persons should work closely with infection-control 
staff to assist in controlling airborne infections.
     Ventilation system designs in health-care facilities 
should meet any applicable federal, state, and local requirements.
     The direction of airflow in health-care facilities should 
be designed, constructed, and maintained so that air flows from clean 
areas to less-clean areas.
     Health-care facilities serving populations that have a 
high prevalence of TB may need to supplement the general ventilation or 
use additional engineering approaches (i.e., HEPA filtration or UVGI) 
in general-use areas where TB patients are likely to go (e.g., waiting-
room areas, emergency departments, and radiology suites). A single-
pass, nonrecirculating system that exhausts air to the outside, a 
recirculation system that passes air through HEPA filters before 
recirculating it to the general ventilation system, or upper air UVGI 
may be used in such areas.
2. Additional Engineering Control Approaches
    a. HEPA filtration.
    HEPA filters may be used in a number of ways to reduce or eliminate 
infectious droplet nuclei from room air or exhaust (Suppl. 3). These 
methods include placement of HEPA filters (a) in exhaust ducts 
discharging air from booths or enclosures into the surrounding room; 
(b) in ducts or in ceiling- or wall-mounted units, for recirculation of 
air within an individual room (fixed recirculation systems); (c) in 
portable air cleaners; (d) in exhaust ducts to remove droplet nuclei 
from air being discharged to the outside, either directly or through 
ventilation equipment; and (e) in ducts discharging air from the TB 
isolation room into the general ventilation system. In any application, 
HEPA filters should be installed carefully and maintained meticulously 
to ensure adequate functioning.
    The manufacturers of in-room air cleaning equipment should provide 
documentation of the HEPA filter efficiency and the efficiency of the 
device in lowering room air contaminant levels.
    b. UVGI.
    For general-use areas in which the risk for transmission of M. 
tuberculosis is relatively high, UVGI lamps may be used as an adjunct 
to ventilation for reducing the concentration of infectious droplet 
nuclei (Suppl. 3), although the effectiveness of such units has not 
been evaluated adequately. Ultraviolet (UV) units can be installed in a 
room or corridor to irradiate the air in the upper portion of the room 
(i.e., upper-room air irradiation), or they can be installed in ducts 
to irradiate air passing through the ducts. UV units installed in ducts 
should not be substituted for HEPA filters in ducts that discharge air 
from TB isolation rooms into the general ventilation system. However, 
UV units can be used in ducts that recirculate air back into the same 
room.
    To function properly and decrease hazards to HCWs and others in the 
health-care facility, UV lamps should be installed properly and 
maintained adequately, which includes the monitoring of irradiance 
levels. UV tubes should be changed according to the manufacturer's 
instructions or when meter readings indicate tube failure. An employee 
trained in the use and handling of UV lamps should be responsible for 
these measures and for keeping maintenance records. Applicable safety 
guidelines should be followed. Caution should be exercised to protect 
HCWs, patients, visitors, and others from excessive exposure to UV 
radiation.
G. Respiratory Protection
     Personal respiratory protection should be used by (a) 
persons entering rooms in which patients with known or suspected 
infectious TB are being isolated, (b) persons present during cough-
inducing or aerosol-generating procedures performed on such patients, 
and (c) persons in other settings where administrative and engineering 
controls are not likely to protect them from inhaling infectious 
airborne droplet nuclei (Suppl. 4). These other settings include 
transporting patients who may have infectious TB in emergency transport 
vehicles and providing urgent surgical or dental care to patients who 
may have infectious TB before a determination has been made that the 
patient is noninfectious (Suppl. 1).
     Respiratory protective devices used in health-care 
settings for protection against M. tuberculosis should meet the 
following standard performance criteria:
    1. The ability to filter particles 1 m in size in the 
unloaded* state with a filter efficiency of 95% (i.e., 
filter leakage of 5%), given flow rates of up to 50 L per 
minute.
---------------------------------------------------------------------------

    *Some filters become more efficient as they become loaded with 
dust. Health-care settings do not have enough dust in the air to 
load a filter on a respirator. Therefore, the filter efficiency for 
respirators used in health-care settings must be determined in the 
unloaded state.
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    2. The ability to be qualitatively or quantitatively fit tested in 
a reliable way to obtain a face-seal leakage of 10% (54,55).
    3. The ability to fit the different facial sizes and 
characteristics of HCWs, which can usually be met by making the 
respirators available in at least three sizes.
    4. The ability to be checked for facepiece fit, in accordance with 
standards established by the Occupational Safety and Health 
Administration (OSHA) and good industrial hygiene practice, by HCWs 
each time they put on their respirators (54,55).
     The facility's risk assessment may identify a limited 
number of selected settings (e.g., bronchoscopy performed on patients 
suspected of having TB or autopsy performed on deceased persons 
suspected of having had active TB at the time of death) where the 
estimated risk for transmission of M. tuberculosis may be such that a 
level of respiratory protection exceeding the standard performance 
criteria is appropriate. In such circumstances, a level of respiratory 
protection exceeding the standard criteria and compatible with patient-
care delivery (e.g., more protective negative-pressure respirators; 
powered air-purifying particulate respirators [PAPRs]; or positive-
pressure air-line, half-mask respirators) should be provided by 
employers to HCWs who are exposed to M. tuberculosis. Information on 
these and other respirators is in the NIOSH Guide to Industrial 
Respiratory Protection (55) and in Supplement 4 of this document.
     In some settings, HCWs may be at risk for two types of 
exposure: (a) inhalation of M. tuberculosis and (b) mucous membrane 
exposure to fluids that may contain bloodborne pathogens. In these 
settings, protection against both types of exposure should be used.
     When operative procedures (or other procedures requiring a 
sterile field) are performed on patients who may have infectious TB, 
respiratory protection worn by the HCW should serve two functions: (a) 
It should protect the surgical field from the respiratory secretions of 
the HCW, and (b) it should protect the HCW from infectious droplet 
nuclei that may be expelled by the patient or generated by the 
procedure. Respirators with exhalation valves and most positive-
pressure respirators do not protect the sterile field.
     Health-care facilities in which respiratory protection is 
used to prevent inhalation of M. tuberculosis are required by OSHA to 
develop, implement, and maintain a respiratory protection program 
(Suppl. 4). All HCWs who use respiratory protection should be included 
in this program. Visitors to TB patients should be given respirators to 
wear while in isolation rooms, and they should be given general 
instructions on how to use their respirators.
     Facilities that do not have isolation rooms and do not 
perform cough-inducing procedures on patients who may have TB may not 
need to have a respiratory protection program for TB. However, such 
facilities should have written protocols for the early identification 
of patients who have signs or symptoms of TB and procedures for 
referring these patients to a facility where they can be evaluated and 
managed appropriately. These protocols should be evaluated regularly 
and revised as needed.
     Surgical masks are designed to prevent the respiratory 
secretions of the person wearing the mask from entering the air. To 
reduce the expulsion of droplet nuclei into the air, patients suspected 
of having TB should wear surgical masks when not in TB isolation rooms. 
These patients do not need to wear particulate respirators, which are 
designed to filter the air before it is inhaled by the person wearing 
the respirator. Patients suspected of having or known to have TB should 
never wear a respirator that has an exhalation valve, because this type 
of respirator does not prevent expulsion of droplet nuclei into the 
air.
H. Cough-Inducing and Aerosol-Generating Procedures
1. General Guidelines
    Procedures that involve instrumentation of the lower respiratory 
tract or induce coughing can increase the likelihood of droplet nuclei 
being expelled into the air. These cough-inducing procedures include 
endotracheal intubation and suctioning, diagnostic sputum induction, 
aerosol treatments (e.g., pentamidine therapy), and bronchoscopy. Other 
procedures that can generate aerosols (e.g., irrigation of tuberculous 
abscesses, homogenizing or lyophilizing tissue, or other processing of 
tissue that may contain tubercle bacilli) are also covered by these 
recommendations.
      Cough-inducing procedures should not be performed on 
patients who may have infectious TB unless the procedures are 
absolutely necessary and can be performed with appropriate precautions.
     All cough-inducing procedures performed on patients who 
may have infectious TB should be performed using local exhaust 
ventilation devices (e.g., booths or special enclosures) or, if this is 
not feasible, in a room that meets the ventilation requirements for TB 
isolation.
     HCWs should wear respiratory protection when present in 
rooms or enclosures in which cough-inducing procedures are being 
performed on patients who may have infectious TB.
     After completion of cough-inducing procedures, patients 
who may have infectious TB should remain in their isolation rooms or 
enclosures and not return to common waiting areas until coughing 
subsides. They should be given tissues and instructed to cover their 
mouths and noses with the tissues when coughing. If TB patients must 
recover from sedatives or anesthesia after a procedure (e.g, after a 
bronchoscopy), they should be placed in separate isolation rooms (and 
not in recovery rooms with other patients) while they are being 
monitored.
     Before the booth, enclosure, or room is used for another 
patient, enough time should be allowed to pass for at least 99% of 
airborne contaminants to be removed. This time will vary according to 
the efficiency of the ventilation or filtration used (Suppl. 3, Table 
S3-1).
2. Special Considerations for Bronchoscopy
     If performing bronchoscopy in positive-pressure rooms 
(e.g., operating rooms) is unavoidable, TB should be ruled out as a 
diagnosis before the procedure is performed. If the bronchoscopy is 
being performed for the purpose of diagnosing pulmonary disease and 
that diagnosis could include TB, the procedure should be performed in a 
room that meets TB isolation ventilation requirements.
3. Special Considerations for the Administration of Aerosolized 
Pentamidine
     Patients should be screened for active TB before 
prophylactic therapy with aerosolized pentamidine is initiated. 
Screening should include obtaining a medical history and performing 
skin testing and chest radiography.
     Before each subsequent treatment with aerosolized 
pentamidine, patients should be screened for symptoms suggestive of TB 
(e.g., development of a productive cough). If such symptoms are 
elicited, a diagnostic evaluation for TB should be initiated.
     Patients who have suspected or confirmed active TB should 
take, if clinically practical, oral prophylaxis for P. carinii 
pneumonia.
I. Education and Training of HCWs
    All HCWs, including physicians, should receive education regarding 
TB that is relevant to persons in their particular occupational group. 
Ideally, training should be conducted before initial assignment, and 
the need for additional training should be reevaluated periodically 
(e.g., once a year). The level and detail of this education will vary 
according to the HCW's work responsibilities and the level of risk in 
the facility (or area of the facility) in which the HCW works. However, 
the program may include the following elements:
     The basic concepts of M. tuberculosis transmission, 
pathogenesis, and diagnosis, including information concerning the 
difference between latent TB infection and active TB disease, the signs 
and symptoms of TB, and the possibility of reinfection.
     The potential for occupational exposure to persons who 
have infectious TB in the health-care facility, including information 
concerning the prevalence of TB in the community and facility, the 
ability of the facility to properly isolate patients who have active 
TB, and situations with increased risk for exposure to M. tuberculosis.
     The principles and practices of infection control that 
reduce the risk for transmission of M. tuberculosis, including 
information concerning the hierarchy of TB infection-control measures 
and the written policies and procedures of the facility. Site-specific 
control measures should be provided to HCWs working in areas that 
require control measures in addition to those of the basic TB 
infection-control program.
     The purpose of PPD skin testing, the significance of a 
positive PPD test result, and the importance of participating in the 
skin-test program.
     The principles of preventive therapy for latent TB 
infection. These principles include the indications, use, 
effectiveness, and the potential adverse effects of the drugs (Suppl. 
2).
     The HCW's responsibility to seek prompt medical evaluation 
if a PPD test conversion occurs or if symptoms develop that could be 
caused by TB. Medical evaluation will enable HCWs who have TB to 
receive appropriate therapy and will help to prevent transmission of M. 
tuberculosis to patients and other HCWs.
     The principles of drug therapy for active TB.
     The importance of notifying the facility if the HCW is 
diagnosed with active TB so that contact investigation procedures can 
be initiated.
     The responsibilities of the facility to maintain the 
confidentiality of the HCW while ensuring that the HCW who has TB 
receives appropriate therapy and is noninfectious before returning to 
duty.
     The higher risks associated with TB infection in persons 
who have HIV infection or other causes of severely impaired cell-
mediated immunity, including (a) the more frequent and rapid 
development of clinical TB after infection with M. tuberculosis, (b) 
the differences in the clinical presentation of disease, and (c) the 
high mortality rate associated with MDR-TB in such persons.
     The potential development of cutaneous anergy as immune 
function (as measured by CD4+ T-lymphocyte counts) declines.
     Information regarding the efficacy and safety of BCG 
vaccination and the principles of PPD screening among BCG recipients.
     The facility's policy on voluntary work reassignment 
options for immunocompromised HCWs.
J. HCW Counseling, Screening, and Evaluation
    A TB counseling, screening, and prevention program for HCWs should 
be established to protect both HCWs and patients. HCWs who have 
positive PPD test results, PPD test conversions, or symptoms suggestive 
of TB should be identified, evaluated to rule out a diagnosis of active 
TB, and started on therapy or preventive therapy if indicated (5). In 
addition, the results of the HCW PPD screening program will contribute 
to evaluation of the effectiveness of current infection-control 
practices.
1. Counseling HCWs Regarding TB
     Because of the increased risk for rapid progression from 
latent TB infection to active TB in HIV-infected or otherwise severely 
immunocompromised persons, all HCWs should know if they have a medical 
condition or are receiving a medical treatment that may lead to 
severely impaired cell-mediated immunity. HCWs who may be at risk for 
HIV infection should know their HIV status (i.e., they should be 
encouraged to voluntarily seek counseling and testing for HIV antibody 
status). Existing guidelines for counseling and testing should be 
followed routinely (56). Knowledge of these conditions allows the HCW 
to seek the appropriate preventive measures outlined in this document 
and to consider voluntary work reassignments. Of particular importance 
is that HCWs need to know their HIV status if they are at risk for HIV 
infection and they work in settings where patients who have drug-
resistant TB may be encountered.
     All HCWs should be informed about the need to follow 
existing recommendations for infection control to minimize the risk for 
exposure to infectious agents; implementation of these recommendations 
will greatly reduce the risk for occupational infections among HCWs 
(57). All HCWs should also be informed about the potential risks to 
severely immunocompromised persons associated with caring for patients 
who have some infectious diseases, including TB. It should be 
emphasized that limiting exposure to TB patients is the most protective 
measure that severely immunosuppressed HCWs can take to avoid becoming 
infected with M. tuberculosis. HCWs who have severely impaired cell-
mediated immunity and who may be exposed to M. tuberculosis may 
consider a change in job setting to avoid such exposure. HCWs should be 
advised of the option that severely immunocompromised HCWs can choose 
to transfer voluntarily to areas and work activities in which there is 
the lowest possible risk for exposure to M. tuberculosis. This choice 
should be a personal decision for HCWs after they have been informed of 
the risks to their health.
     Employers should make reasonable accommodations (e.g., 
alternative job assignments) for employees who have a health condition 
that compromises cell-mediated immunity and who work in settings where 
they may be exposed to M. tuberculosis. HCWs who are known to be 
immunocompromised should be referred to employee health professionals 
who can individually counsel the employees regarding their risk for TB. 
Upon the request of the immunocompromised HCW, employers should offer, 
but not compel, a work setting in which the HCW would have the lowest 
possible risk for occupational exposure to M. tuberculosis. Evaluation 
of these situations should also include consideration of the provisions 
of the Americans With Disabilities Act of 1990* and other applicable 
federal, state, and local laws.
---------------------------------------------------------------------------

    *Americans With Disabilities Act of 1990. P.L. 101-336, 42 
U.S.C. 12101 et seq.
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     All HCWs should be informed that immunosuppressed HCWs 
should have appropriate follow-up and screening for infectious 
diseases, including TB, provided by their medical practitioner. HCWs 
who are known to be HIV-infected or otherwise severely immunosuppressed 
should be tested for cutaneous anergy at the time of PPD testing 
(Suppl. 2). Consideration should be given to retesting, at least every 
6 months, those immunocompromised HCWs who are potentially exposed to 
M. tuberculosis because of the high risk for rapid progression to 
active TB if they become infected.
     Information provided by HCWs regarding their immune status 
should be treated confidentially. If the HCW requests voluntary job 
reassignment, the confidentiality of the HCW should be maintained. 
Facilities should have written procedures on confidential handling of 
such information.
2. Screening HCWs for Active TB
     Any HCW who has a persistent cough (i.e., a cough lasting 
3 weeks), especially in the presence of other signs or 
symptoms compatible with active TB (e.g., weight loss, night sweats, 
bloody sputum, anorexia, or fever), should be evaluated promptly for 
TB. The HCW should not return to the workplace until a diagnosis of TB 
has been excluded or until the HCW is on therapy and a determination 
has been made that the HCW is noninfectious.
3. Screening HCWs for Latent TB Infection
     The risk assessment should identify which HCWs have 
potential for exposure to M. tuberculosis and the frequency with which 
the exposure may occur. This information is used to determine which 
HCWs to include in the skin-testing program and the frequency with 
which they should be tested (Table 2).
     If HCWs are from risks groups with increased prevalence of 
TB, consideration may be given to including them in the skin-testing 
program, even if they do not have potential occupational exposure to M. 
tuberculosis, so that converters can be identified and preventive 
therapy offered.
     Administrators of health-care facilities should ensure 
that physicians and other personnel not paid by, but working in, the 
facility receive skin testing at appropriate intervals for their 
occupational group and work location.
     During the pre-employment physical or when applying for 
hospital privileges, HCWs who have potential for exposure to M. 
tuberculosis (Table 2), including those with a history of BCG 
vaccination, should have baseline PPD skin testing performed (Suppl. 
2). For HCWs who have not had a documented negative PPD test result 
during the preceding 12 months, the baseline PPD testing should employ 
the two-step method; this will detect boosting phenomena that might be 
misinterpreted as a skin-test conversion. Decisions concerning the use 
of the two-step procedure for baseline testing in a particular facility 
should be based on the frequency of boosting in that facility.
     HCWs who have a documented history of a positive PPD test, 
adequate treatment for disease, or adequate preventive therapy for 
infection, should be exempt from further PPD screening unless they 
develop signs or symptoms suggestive of TB.
     PPD-negative HCWs should undergo repeat PPD testing at 
regular intervals as determined by the risk assessment (Section II.B). 
In addition, these HCWs should be tested whenever they have been 
exposed to a TB patient and appropriate precautions were not observed 
at the time of exposure (Section II.K.3). Performing PPD testing of 
HCWs who work in the same area or occupational group on different 
scheduled dates (e.g., test them on their birthdays or on their 
employment anniversary dates), rather than testing all HCWs in the area 
or group on the same day, may lead to earlier detection of M. 
tuberculosis transmission.
     All PPD tests should be administered, read, and 
interpreted in accordance with current guidelines by specified trained 
personnel (Suppl. 2). At the time their test results are read, HCWs 
should be informed about the interpretation of both positive and 
negative PPD test results. This information should indicate that the 
interpretation of an induration that is 5-9 mm in diameter depends on 
the HCW's immune status and history of exposure to persons who have 
infectious TB. Specifically, HCWs who have indurations of 5-9 mm in 
diameter should be advised that such results may be considered positive 
for HCWs who are contacts of persons with infectious TB or who have HIV 
infection or other causes of severe immunosuppression (e.g., 
immunosuppressive therapy for organ transplantation).
     When an HCW who is not assigned regularly to a single work 
area has a PPD test conversion, appropriate personnel should identify 
the areas where the HCW worked during the time when infection was 
likely to have occurred. This information can then be considered in 
analyzing the risk for transmission in those areas.
     In any area of the facility where transmission of M. 
tuberculosis is known to have occurred, a problem evaluation should be 
conducted (Section II.K), and the frequency of skin testing should be 
determined according to the applicable risk category (Section II.B).
     PPD test results should be recorded confidentially in the 
individual HCW's employee health record and in an aggregate database of 
all HCW PPD test results. The database can be analyzed periodically to 
estimate the risk for acquiring new infection in specific areas or 
occupational groups in the facility.
4. Evaluation and Management of HCWs Who Have Positive PPD Test Results 
or Active TB
    a. Evaluation
     All HCWs with newly recognized positive PPD test results 
or PPD test conversions should be evaluated promptly for active TB. 
This evaluation should include a clinical examination and a chest 
radiograph. If the history, clinical examination, or chest radiograph 
is compatible with active TB, additional tests should be performed 
(Section II.C.2). If symptoms compatible with TB are present, the HCW 
should be excluded from the workplace until either a) a diagnosis of 
active TB is ruled out or b) a diagnosis of active TB was established, 
the HCW is being treated, and a determination has been made that the 
HCW is noninfectious (Suppl. 2). HCWs who do not have active TB should 
be evaluated for preventive therapy according to published guidelines 
(Suppl. 2).
     If an HCW's PPD test result converts to positive, a 
history of confirmed or suspected TB exposure should be obtained in an 
attempt to determine the potential source. When the source of exposure 
is known, the drug-susceptibility pattern of the M. tuberculosis 
isolated from the source should be identified so that the correct 
curative or preventive therapy can be initiated for the HCW with the 
PPD test conversion. The drug-susceptibility pattern should be recorded 
in the HCW's medical record, where it will be available if the HCW 
subsequently develops active TB and needs therapy specific for the 
drug-susceptibility pattern.
     All HCWs, including those with histories of positive PPD 
test results, should be reminded periodically about the symptoms of TB 
and the need for prompt evaluation of any pulmonary symptoms suggestive 
of TB.
    b. Routine and follow-up chest radiographs.
     Routine chest radiographs are not required for 
asymptomatic, PPD-negative HCWs. HCWs with positive PPD test results 
should have a chest radiograph as part of the initial evaluation of 
their PPD test; if negative, repeat chest radiographs are not needed 
unless symptoms develop that could be attributed to TB (58). However, 
more frequent monitoring for symptoms of TB may be considered for 
recent converters and other PPD-positive HCWs who are at increased risk 
for developing active TB (e.g., HIV-infected or otherwise severely 
immunocompromised HCWs).
    c. Workplace restrictions.
    (1) Active TB.
     HCWs with pulmonary or laryngeal TB pose a risk to 
patients and other HCWs while they are infectious, and they should be 
excluded from the workplace until they are noninfectious. The same work 
restrictions apply to all HCWs regardless of their immune status.
     Before the HCW who has TB can return to the workplace, the 
health-care facility should have documentation from the HCW's health-
care provider that the HCW is receiving adequate therapy, the cough has 
resolved, and the HCW has had three consecutive negative sputum smears 
collected on different days. After work duties are resumed and while 
the HCW remains on anti-TB therapy, facility staff should receive 
periodic documentation from the HCW's health-care provider that the HCW 
is being maintained on effective drug therapy for the recommended time 
period and that the sputum AFB smears continue to be negative.
     HCWs with active laryngeal or pulmonary TB who discontinue 
treatment before they are cured should be evaluated promptly for 
infectiousness. If the evaluation determines that they are still 
infectious, they should be excluded from the workplace until treatment 
has been resumed, an adequate response to therapy has been documented, 
and three more consecutive sputum AFB smears collected on different 
days have been negative.
     HCWs who have TB at sites other than the lung or larynx 
usually do not need to be excluded from the workplace if a diagnosis of 
concurrent pulmonary TB has been ruled out.
    (2) Latent TB infection.
     HCWs receiving preventive treatment for latent TB 
infection should not be restricted from their usual work activities.
     HCWs with latent TB infection who cannot take or who do 
not accept or complete a full course of preventive therapy should not 
be excluded from the workplace. These HCWs should be counseled about 
the risk for developing active TB and instructed regularly to seek 
prompt evaluation if signs or symptoms develop that could be caused by 
TB.
K. Problem Evaluation
    Epidemiologic investigations may be indicated for several 
situations. These include, but are not limited to, (a) the occurrence 
of PPD test conversions or active TB in HCWs; (b) the occurrence of 
possible person-to-person transmission of M. tuberculosis; and (c) 
situations in which patients or HCWs with active TB are not promptly 
identified and isolated, thus exposing other persons in the facility to 
M. tuberculosis. The general objectives of the epidemiologic 
investigations in these situations are as follows:
    (1) To determine the likelihood that transmission of and infection 
with M. tuberculosis has occurred in the facility;
    (2) To determine the extent to which M. tuberculosis has been 
transmitted;
    (3) To identify those persons who have been exposed and infected, 
enabling them to receive appropriate clinical management;
    (4) To identify factors that could have contributed to transmission 
and infection and to implement appropriate interventions; and
    (5) To evaluate the effectiveness of any interventions that are 
implemented and to ensure that exposure to and transmission of M. 
tuberculosis have been terminated.
    The exact circumstances of these situations are likely to vary 
considerably, and the associated epidemiologic investigations should be 
tailored to the individual circumstances. The following sections 
provide general guidance for conducting these investigations.
1. Investigating PPD Test Conversions and Active TB in HCWs
    a. Investigating PPD test conversions in HCWs.
    PPD test conversions may be detected in HCWs as a result of a 
contact investigation, in which case the probable source of exposure 
and transmission is already known (Section II.K.3.), or as a result of 
routine screening, in which case the probable source of exposure and 
infection is not already known and may not be immediately apparent.
    If a skin-test conversion in an HCW is identified as part of 
routine screening, the following steps should be considered (Figure 2):
     The HCW should be evaluated promptly for active TB. The 
initial evaluation should include a thorough history, physical 
examination, and chest radiograph. On the basis of the initial 
evaluation, other diagnostic procedures (e.g., sputum examination) may 
be indicated.
     If appropriate, the HCW should be placed on preventive or 
curative therapy in accordance with current guidelines (Suppl. 2) (5).
     A history of possible exposure to M. tuberculosis should 
be obtained from the HCW to determine the most likely source of 
infection. When the source of infection is known, the drug-
susceptibility pattern of the M. tuberculosis isolate from the source 
patient should be identified to determine appropriate preventive or 
curative therapy regimens.
     If the history suggests that the HCW was exposed to and 
infected with M. tuberculosis outside the facility, no further 
epidemiologic investigation to identify a source in the facility is 
necessary.
     If the history does not suggest that the HCW was exposed 
and infected outside the facility but does identify a probable source 
of exposure in the facility, contacts of the suspected source patient 
should be identified and evaluated. Possible reasons for the exposure 
and transmission should be evaluated (Table 4), interventions should be 
implemented to correct these causes, and PPD testing of PPD-negative 
HCWs should be performed immediately and repeated after 3 months.
    If no additional PPD test conversions are detected on follow-up 
testing, the investigation can be terminated.
    If additional PPD test conversions are detected on follow-up 
testing, the possible reasons for exposure and transmission should be 
reassessed, the appropriateness of and degree of adherence to the 
interventions implemented should be evaluated, and PPD testing of PPD-
negative HCWs should be repeated after another 3 months.
    If no additional PPD test conversions are detected on the second 
round of follow-up testing, the investigation can be terminated. 
However, if additional PPD conversions are detected on the second round 
of follow-up testing, a high-risk protocol should be implemented in the 
affected area or occupational group, and the public health department 
or other persons with expertise in TB infection control should be 
consulted.
     If the history does not suggest that the HCW was exposed 
to and infected with M. tuberculosis outside the facility and does not 
identify a probable source of exposure in the facility, further 
investigation to identify the probable source patient in the facility 
is warranted.
    The interval during which the HCW could have been infected should 
be estimated. Generally, this would be the interval from 10 weeks 
before the most recent negative PPD test through 2 weeks before the 
first positive PPD test (i.e., the conversion).
    Laboratory and infection-control records should be reviewed to 
identify all patients or HCWs who have suspected or confirmed 
infectious TB and who could have transmitted M. tuberculosis to the 
HCW.
    If this process does identify a likely source patient, contacts of 
the suspected source patient should be identified and evaluated, and 
possible reasons for the exposure and transmission should be evaluated 
(Table 4). Interventions should be implemented to correct these causes, 
and PPD testing of PPD-negative HCWs should be repeated after 3 months. 
However, if this process does not identify a probable source case, PPD 
screening results of other HCWs in the same area or occupational group 
should be reviewed for additional evidence of M. tuberculosis 
transmission. If sufficient additional PPD screening results are not 
available, appropriate personnel should consider conducting additional 
PPD screening of other HCWs in the same area or occupational group.

BILLING CODE 4163-18-P

TN28OC94.002


TN28OC94.003


BILLING CODE 4163-18-C

   Table 4.--Examples of Potential Problems That Can Occur When Identifying or Isolating Patients Who May Have  
                                          Infectious Tuberculosis (TB)                                          
----------------------------------------------------------------------------------------------------------------
       Situation                   Potential problem                              Intervention                  
----------------------------------------------------------------------------------------------------------------
Patient identification   Patient with signs or symptoms not      Review triage procedures, facilities, and      
 during triage            identified.                             practices.                                    
                         Patient had no symptoms listed in       Revaluate triage protocol.                     
                          triage protocol.                                                                      
During review of         Positive smear: results available >24   Change laboratory practices. Assess potential  
 laboratory results       hours* after submitted.                 barriers. Explore alternatives.               
                         Positive smear: results available but   Educate appropriate personnel. Review protocol 
                          action not taken promptly.              for management of positive smear results.     
                         Positive culture: results not           Change laboratory practices. Assess potential  
                          available for >3 weeks*.                barriers. Explore alternatives.               
                         Postive culture: results available but  Educate appropriate personnel. Review protocol 
                          action not taken promptly.              for management of positive culture results.   
                         Positive culture: susceptibility        Change laboratory practices. Assess potential  
                          results not available for >6 weeks*.    barriers. Explore alternatives.               
                         Positive culture: susceptibility        Educate appropriate personnel. Review protocol 
                          results available but action not        for management of positive culture            
                          taken promptly.                         susceptibility results.                       
At time of diagnosis     Patient with signs/symptoms of TB:      Educate appropriate personnel. Evaluate        
 and during isolation     appropriate tests not ordered           protocols for TB detection.                   
                          promptly.                                                                             
                         Isolation room unavailable............  Reassess need for number of isolation rooms.   
                         Isolation not ordered or discontinued   Educate patients and appropriate personnel.    
                          too soon, or isolation policy not       Evaluate institutional barriers to            
                          followed properly (e.g., patients       implementation of isolation policy.           
                          going outside of room).                                                               
                         Personnel not properly using            Educate appropriate personnel. Evaluate        
                          respiratory protection.                 regularly scheduled re-education. Evaluate    
                                                                  institutional barriers to use of respiratory  
                                                                  protection.                                   
                         Isolation room or procedure room not    Make appropriate engineering modifications.    
                          at negative pressure reslative to       Establish protocols for regularly monitoring  
                          surrounding areas.                      and maintaining negative pressure.            
                         Inadequate air circulation............  Make appropriate engineering modifications.    
                         Door left open........................  Educate appropriate personnel and patients.    
                                                                  Evaluate self-closing doors, comfort levels in
                                                                  the room, and other measures to promote door  
                                                                  closing.                                      
----------------------------------------------------------------------------------------------------------------
*These time intervals are used as examples and should not be considered absolute standards.                     

    If this review and/or screening does not identify additional PPD 
conversions, nosocomial transmission is less likely, and the contact 
investigation can probably be terminated. Whether the HCW's PPD test 
conversion resulted from occupational exposure and infection is 
uncertain; however, the absence of other data implicating nosocomial 
transmission suggests that the conversion could have resulted from (a) 
unrecognized exposure to M. tuberculosis outside the facility; (b) 
cross-reactivity with another antigen (e.g., nontuberculous 
mycobacteria); (c) errors in applying, reading, or interpreting the 
test; (d) false positivity caused by the normal variability of the 
test; or (e) false positivity caused by a defective PPD preparation.
    If this review and/or screening does identify additional PPD test 
conversions, nosocomial transmission is more likely. In this situation, 
the patient identification (i.e., triage) process, TB infection-control 
policies and practices, and engineering controls should be evaluated to 
identify problems that could have led to exposure and transmission 
(Table 4).
    If no such problems are identified, a high-risk protocol should be 
implemented in the affected area or occupational group, and the public 
health department or other persons with expertise in TB infection 
control should be consulted.
    If such problems are identified, appropriate interventions should 
be implemented to correct the problem(s), and PPD skin testing of PPD-
negative HCWs should be repeated after 3 months.
    If no additional PPD conversions are detected on follow-up testing, 
the investigation can be terminated.
    If additional PPD conversions are detected on follow-up testing, 
the possible reasons for exposure and transmission should be 
reassessed, the appropriateness of and adherence to the interventions 
implemented should be evaluated, and PPD skin testing of PPD-negative 
HCWs should be repeated after another 3 months.
    If no additional PPD test conversions are detected on this second 
round of follow-up testing, the investigation can be terminated. 
However, if additional PPD test conversions are detected on the second 
round of follow-up testing, a high-risk protocol should be implemented 
in the affected area or occupational group, and the public health 
department or other persons with expertise in TB infection control 
should be consulted.
    b. Investigating cases of active TB in HCWs.
    If an HCW develops active TB, the following steps should be taken:
     The case should be evaluated epidemiologically, in a 
manner similar to PPD test conversions in HCWs, to determine the 
likelihood that it resulted from occupational transmission and to 
identify possible causes and implement appropriate interventions if the 
evaluation suggests such transmission.
     Contacts of the HCW (e.g., other HCWs, patients, visitors, 
and others who have had intense exposure to the HCW) should be 
identified and evaluated for TB infection and disease (Section II.K.3; 
Suppl. 2). The public health department should be notified immediately 
for consultation and to allow for investigation of community contacts 
who were not exposed in the health-care facility.
     The public health department should notify facilities when 
HCWs with TB are reported by physicians so that an investigation of 
contacts can be conducted in the facility. The information provided by 
the health department to facilities should be in accordance with state 
or local laws to protect the confidentiality of the HCW.
2. Investigating Possible Patient-to-Patient Transmission of M. 
tuberculosis
    Surveillance of active TB cases in patients should be conducted. If 
this surveillance suggests the possibility of patient-to-patient 
transmission of M. tuberculosis (e.g., a high proportion of TB patients 
had prior admissions during the year preceding onset of their TB, the 
number of patients with drug-resistant TB increased suddenly, or 
isolates obtained from multiple patients had identical and 
characteristic drug-susceptibility or DNA fingerprint patterns), the 
following steps should be taken:
     Review the HCW PPD test results and patient surveillance 
data for the suspected areas to detect additional patients or HCWs with 
PPD test conversions or active disease.
     Look for possible exposures that patients with newly 
diagnosed TB could have had to other TB patients during previous 
admissions. For example, were the patients admitted to the same room or 
area, or did they receive the same procedure or go to the same 
treatment area on the same day?
    If the evaluation thus far suggests transmission has occurred, the 
following steps should be taken:
     Evaluate possible causes of the transmission (e.g., 
problem with patient detection, institutional barriers to implementing 
appropriate isolation practices, or inadequate engineering controls) 
(Table 4).
     Ascertain whether other patients or HCWs could have been 
exposed; if so, evaluate these persons for TB infection and disease 
(Section II.K.3; Suppl. 2).
     Notify the public health department so they can begin a 
community contact investigation if necessary.
3. Investigating Contacts of Patients and HCWs Who Have Infectious TB
    If a patient who has active TB is examined in a health-care 
facility and the illness is not diagnosed correctly, resulting in 
failure to apply appropriate precautions, or if an HCW develops active 
TB and exposes other persons in the facility, the following steps 
should be taken when the illness is later diagnosed correctly:
     To identify other patients and HCWs who were exposed to 
the source patient before isolation procedures were begun, interview 
the source patient and all applicable personnel and review that 
patient's medical record. Determine the areas of the facility in which 
the source patient was hospitalized, visited, or worked before being 
placed in isolation (e.g., outpatient clinics, hospital rooms, 
treatment rooms, radiology and procedure areas, and patient lounges) 
and the HCWs who may have been exposed during that time (e.g., persons 
providing direct care, therapists, clerks, transportation personnel, 
housekeepers, and social workers).
     The contact investigation should first determine if M. 
tuberculosis transmission has occurred from the source patient to those 
persons with whom the source patient had the most intense contact.
     Administer PPD tests to the most intensely exposed HCWs 
and patients as soon as possible after the exposure has occurred. If 
transmission did occur to the most intensely exposed persons, then 
those persons with whom the patient had less contact should be 
evaluated. If the initial PPD test result is negative, a second test 
should be administered 12 weeks after the exposure was terminated.
     Those persons who were exposed to M. tuberculosis and who 
have either a PPD test conversion or symptoms suggestive of TB should 
receive prompt clinical evaluation and, if indicated, chest radiographs 
and bacteriologic studies should be performed (Suppl. 2). Those persons 
who have evidence of newly acquired infection or active disease should 
be evaluated for preventive or curative therapy (Suppl. 2). Persons who 
have previously had positive PPD test results and who have been exposed 
to an infectious TB patient do not require a repeat PPD test or a chest 
radiograph unless they have symptoms suggestive of TB.
     In addition to PPD testing those HCWs and patients who 
have been exposed to M. tuberculosis because a patient was not isolated 
promptly or an HCW with active TB was not identified promptly, the 
investigation should determine why the diagnosis of TB was delayed. If 
the correct diagnosis was made but the patient was not isolated 
promptly, the reasons for the delay need to be defined so that 
corrective actions can be taken.
L. Coordination With the Public Health Department
     As soon as a patient or HCW is known or suspected to have 
active TB, the patient or HCW should be reported to the public health 
department so that appropriate follow-up can be arranged and a 
community contact investigation can be performed. The health department 
should be notified well before patient discharge to facilitate follow-
up and continuation of therapy. A discharge plan coordinated with the 
patient or HCW, the health department, and the inpatient facility 
should be implemented.
     The public health department should protect the 
confidentiality of the patient or HCW in accordance with state and 
local laws.
     Health-care facilities and health departments should 
coordinate their efforts to perform appropriate contact investigations 
on patients and HCWs who have active TB.
     In accordance with state and local laws and regulations, 
results of all AFB-positive sputum smears, cultures positive for M. 
tuberculosis, and drug-susceptibility results on M. tuberculosis 
isolates should be reported to the public health department as soon as 
these results are available.
     The public health department may be able to assist 
facilities with planning and implementing various aspects of a TB 
infection-control program (e.g., surveillance, screening activities, 
and outbreak investigations). In addition, the state health department 
may be able to provide names of experts to assist with the engineering 
aspects of TB infection control.
M. Additional Considerations for Selected Areas in Health-Care 
Facilities and Other Health-Care Settings
    This section contains additional information for selected areas in 
health-care facilities and for other health-care settings.
1. Selected Areas in Health-Care Facilities
    a. Operating rooms.
     Elective operative procedures on patients who have TB 
should be delayed until the patient is no longer infectious.
     If operative procedures must be performed, they should be 
done, if possible, in operating rooms that have anterooms. For 
operating rooms without anterooms, the doors to the operating room 
should be closed, and traffic into and out of the room should be 
minimal to reduce the frequency of opening and closing the door. 
Attempts should be made to perform the procedure at a time when other 
patients are not present in the operative suite and when a minimum 
number of personnel are present (e.g., at the end of day).
     Placing a bacterial filter on the patient endotracheal 
tube (or at the expiratory side of the breathing circuit of a 
ventilator or anesthesia machine if these are used) when operating on a 
patient who has confirmed or suspected TB may help reduce the risk for 
contaminating anesthesia equipment or discharging tubercle bacilli into 
the ambient air.
     During postoperative recovery, the patient should be 
monitored and should be placed in a private room that meets recommended 
standards for ventilating TB isolation rooms.
     When operative procedures (or other procedures requiring a 
sterile field) are performed on patients who may have infectious TB, 
respiratory protection worn by the HCW must protect the field from the 
respiratory secretions of the HCW and protect the HCW from the 
infectious droplet nuclei generated by the patient. Valved or positive-
pressure respirators do not protect the sterile field; therefore, a 
respirator that does not have a valve and that meets the criteria in 
Section II.G should be used.
    b. Autopsy rooms.
     Because infectious aerosols are likely to be present in 
autopsy rooms, such areas should be at negative pressure with respect 
to adjacent areas (Suppl. 3), and the room air should be exhausted 
directly to the outside of the building. ASHRAE recommends that autopsy 
rooms have ventilation that provides an airflow of 12 ACH (47), 
although the effectiveness of this ventilation level in reducing the 
risk for M. tuberculosis, transmission has not been evaluated. Where 
possible, this level should be increased by means of ventilation system 
design or by auxiliary methods (e.g., recirculation of air within the 
room through HEPA filters) (Suppl. 3).
     Respiratory protection should be worn by personnel while 
performing autopsies on deceased persons who may have had TB at the 
time of death (Section II.G; Suppl. 4).
     Recirculation of HEPA-filtered air within the room or UVGI 
may be used as a supplement to the recommended ventilation (Suppl. 3).
    c. Laboratories.
     Laboratories in which specimens for mycobacteriologic 
studies (e.g., AFB smears and cultures) are processed should be 
designed to conform with criteria specified by CDC and the National 
Institutes of Health (59).
2. Other Health-Care Settings
    TB precautions may be appropriate in a number of other types of 
health care settings. The specific precautions that are applied will 
vary depending on the setting. At a minimum, a risk assessment should 
be performed yearly for these settings; a written TB infection-control 
plan should be developed, evaluated, and revised on a regular basis; 
protocols should be in place for identifying and managing patients who 
may have active TB; HCWs should receive appropriate training, 
education, and screening; protocols for problem evaluation should be in 
place; and coordination with the public health department should be 
arranged when necessary. Other recommendations specific to certain of 
these settings follow.
    a. Emergency medical services.
     When EMS personnel or others must transport patients who 
have confirmed or suspected active TB, a surgical mask should be 
placed, if possible, over the patient's mouth and nose. Because 
administrative and engineering controls during emergency transport 
situations cannot be ensured, EMS personnel should wear respiratory 
protection when transporting such patients. If feasible, the windows of 
the vehicle should be kept open. The heating and air-conditioning 
system should be set on a nonrecirculating cycle.
     EMS personnel should be included in a comprehensive PPD 
screening program and should receive a baseline PPD test and follow-up 
testing as indicated by the risk assessment. They should also be 
included in the follow-up of contacts of a patient with infectious TB.*
---------------------------------------------------------------------------

    *The Ryan White Comprehensive AIDS Resource Emergency Act of 
1990, P.L. 101-381, mandates notification of EMS personnel after 
they have been exposed to infectious pulmonary TB (42 U.S.C. 300ff-
82. 54 FR 13417 [March 21, 1994]).
---------------------------------------------------------------------------

    b. Hospices.
     Hospice patients who have confirmed or suspected TB should 
be managed in the manner described in this document for management of 
TB patients in hospitals. General-use and specialized areas (e.g., 
treatment or TB isolation rooms) should be ventilated in the same 
manner as described for similar hospital areas.
    c. Long-term care facilities.
     Recommendations published previously for preventing and 
controlling TB in long-term care facilities should be followed (60).
     Long-term care facilities should also follow the 
recommendations outlined in this document.
    d. Correctional facilities.
     Recommendations published previously for preventing and 
controlling TB in correctional facilities should be followed (61).
     Prison medical facilities should also follow the 
recommendations outlined in this document.
    e. Dental settings.
    In general, the symptoms for which patients seek treatment in a 
dental-care setting are not likely to be caused by infectious TB. 
Unless a patient requiring dental care coincidentally has TB, it is 
unlikely that infectious TB will be encountered in the dental setting. 
Furthermore, generation of droplet nuclei containing M. tuberculosis 
during dental procedures has not been demonstrated (62). Therefore, the 
risk for transmission of M. tuberculosis in most dental settings is 
probably quite low. Nevertheless, during dental procedures, patients 
and dental workers share the same air for varying periods of time. 
Coughing may be stimulated occasionally by oral manipulations, although 
no specific dental procedures have been classified as ``cough-
inducing.'' In some instances, the population served by a dental-care 
facility, or the HCWs in the facility, may be at relatively high risk 
for TB. Because the potential exists for transmission of M. 
tuberculosis in dental settings, the following recommendations should 
be followed:
     A risk assessment (Section II.B) should be done 
periodically, and TB infection-control policies for each dental setting 
should be based on the risk assessment. The policies should include 
provisions for detection and referral of patients who may have 
undiagnosed active TB; management of patients with active TB, relative 
to provision of urgent dental care; and employer-sponsored HCW 
education, counseling, and screening.
     While taking patients' initial medical histories and at 
periodic updates, dental HCWs should routinely ask all patients whether 
they have a history of TB disease and symptoms suggestive of TB.
     Patients with a medical history or symptoms suggestive of 
undiagnosed active TB should be referred promptly for medical 
evaluation of possible infectiousness. Such patients should not remain 
in the dental-care facility any longer than required to arrange a 
referral. While in the dental-care facility, they should wear surgical 
masks and should be instructed to cover their mouths and noses when 
coughing or sneezing.
     Elective dental treatment should be deferred until a 
physician confirms that the patient does not have infectious TB. If the 
patient is diagnosed as having active TB, elective dental treatment 
should be deferred until the patient is no longer infectious.
     If urgent dental care must be provided for a patient who 
has, or is strongly suspected of having, infectious TB, such care 
should be provided in facilities that can provide TB isolation 
(Sections II.E and G). Dental HCWs should use respiratory protection 
while performing procedures on such patients.
     Any dental HCW who has a persistent cough (i.e., a cough 
lasting 3 weeks), especially in the presence of other signs 
or symptoms compatible with active TB (e.g., weight loss, night sweats, 
bloody sputum, anorexia, and fever), should be evaluated promptly for 
TB. The HCW should not return to the workplace until a diagnosis of TB 
has been excluded or until the HCW is on therapy and a determination 
has been made that the HCW is noninfectious.
     In dental-care facilities that provide care to populations 
at high risk for active TB, it may be appropriate to use engineering 
controls similar to those used in general-use areas (e.g., waiting 
rooms) of medical facilities that have a similar risk profile.
    f. Home-health-care settings.
     HCWs who provide medical services in the homes of patients 
who have suspected or confirmed infectious TB should instruct such 
patients to cover their mouths and noses with a tissue when coughing or 
sneezing. Until such patients are no longer infectious, HCWs should 
wear respiratory protection when entering these patients' homes (Suppl. 
4).
     Precautions in the home may be discontinued when the 
patient is no longer infectious (Suppl. 1).
     HCWs who provide health-care services in their patients' 
homes can assist in preventing transmission of M. tuberculosis by 
educating their patients regarding the importance of taking medications 
as prescribed and by administering DOT.
     Cough-inducing procedures performed on patients who have 
infectious TB should not be done in the patients' homes unless 
absolutely necessary. When medically necessary cough-inducing 
procedures (e.g., AFB sputum collection for evaluation of therapy) must 
be performed on patients who may have infectious TB, the procedures 
should be performed in a health-care facility in a room or booth that 
has the recommended ventilation for such procedures. If these 
procedures must be performed in a patient's home, they should be 
performed in a well-ventilated area away from other household members. 
If feasible, the HCW should consider opening a window to improve 
ventilation or collecting the specimen while outside the dwelling. The 
HCW collecting these specimens should wear respiratory protection 
during the procedure (Section II.G).
     HCWs who provide medical services in their patients' homes 
should be included in comprehensive employer-sponsored TB training, 
education, counseling, and screening programs. These programs should 
include provisions for identifying HCWs who have active TB, baseline 
PPD skin testing, and follow-up PPD testing at intervals appropriate to 
the degree of risk.
     Patients who are at risk for developing active TB and the 
HCWs who provide medical services in the homes of such patients should 
be reminded periodically of the importance of having pulmonary symptoms 
evaluated promptly to permit early detection of and treatment for TB.
    g. Medical offices.
    In general, the symptoms of active TB are symptoms for which 
patients are likely to seek treatment in a medical office. Furthermore, 
the populations served by some medical offices, or the HCWs in the 
office, may be at relatively high risk for TB. Thus, it is likely that 
infectious TB will be encountered in a medical office. Because of the 
potential for M. tuberculosis transmission, the following 
recommendations should be observed:
     A risk assessment should be conducted periodically, and TB 
infection-control policies based on results of the risk assessment 
should be developed for the medical office. The policies should include 
provisions for identifying and managing patients who may have 
undiagnosed active TB; managing patients who have active TB; and 
educating, training, counseling, and screening HCWs.
     While taking patients' initial medical histories and at 
periodic updates, HCWs who work in medical offices should routinely ask 
all patients whether they have a history of TB disease or have had 
symptoms suggestive of TB.
     Patients with a medical history and symptoms suggestive of 
active TB should receive an appropriate diagnostic evaluation for TB 
and be evaluated promptly for possible infectiousness. Ideally, this 
evaluation should be done in a facility that has TB isolation 
capability. At a minimum, the patient should be provided with and asked 
to wear a surgical mask, instructed to cover the mouth and nose with a 
tissue when coughing or sneezing, and separated as much as possible 
from other patients.
     Medical offices that provide evaluation or treatment 
services for TB patients should follow the recommendations for managing 
patients in ambulatory-care settings (Section II.D).
     If cough-inducing procedures are to be administered in a 
medical office to patients who may have active TB, appropriate 
precautions should be followed (Section II.H).
     Any HCW who has a persistent cough (i.e., a cough lasting 
3 weeks), especially in the presence of other signs or 
symptoms compatible with active TB (e.g., weight loss, night sweats, 
bloody sputum, anorexia, or fever) should be evaluated promptly for TB. 
HCWs with such signs or symptoms should not return to the workplace 
until a diagnosis of TB has been excluded or until they are on therapy 
and a determination has been made that they are noninfectious.
     HCWs who work in medical offices in which there is a 
likelihood of exposure to patients who have infectious TB should be 
included in employer-sponsored education, training, counseling, and PPD 
testing programs appropriate to the level of risk in the office.
     In medical offices that provide care to populations at 
relatively high risk for active TB, use of engineering controls as 
described in this document for general-use areas (e.g., waiting rooms) 
may be appropriate (Section II.F; Suppl. 3).

Supplement 1: Determining the Infectiousness of a TB Patient

    The infectiousness of patients with TB correlates with the number 
of organisms expelled into the air, which, in turn, correlates with the 
following factors: (a) Disease in the lungs, airways, or larynx; (b) 
presence of cough or other forceful expiratory measures; (c) presence 
of acid-fast bacilli (AFB) in the sputum; (d) failure of the patient to 
cover the mouth and nose when coughing; (e) presence of cavitation on 
chest radiograph; (f) inappropriate or short duration of chemotherapy; 
and (g) administration of procedures that can induce coughing or cause 
aerosolization of M. tuberculosis (e.g., sputum induction).
    The most infectious persons are most likely those who have not been 
treated for TB and who have either (a) pulmonary or laryngeal TB and a 
cough or are undergoing cough-inducing procedures, (b) a positive AFB 
sputum smear, or (c) cavitation on chest radiograph. Persons with 
extrapulmonary TB usually are not infectious unless they have (a) 
concomitant pulmonary disease; (b) nonpulmonary disease located in the 
respiratory tract or oral cavity; or (c) extrapulmonary disease that 
includes an open abscess or lesion in which the concentration of 
organisms is high, especially if drainage from the abscess or lesion is 
extensive (20,22). Coinfection with HIV does not appear to affect the 
infectiousness of TB patients (63-65).
    In general, children who have TB may be less likely than adults to 
be infectious; however, transmission from children can occur. 
Therefore, children with TB should be evaluated for infectiousness 
using the same parameters as for adults (i.e., pulmonary or laryngeal 
TB, presence of cough or cough-inducing procedures, positive sputum AFB 
smear, cavitation on chest radiograph, and adequacy and duration of 
therapy). Pediatric patients who may be infectious include those who 
(a) are not on therapy, (b) have just been started on therapy, or (c) 
are on inadequate therapy, and who (a) have laryngeal or extensive 
pulmonary involvement, (b) have pronounced cough or are undergoing 
cough-inducing procedures, (c) have positive sputum AFB smears, or (d) 
have cavitary TB. Children who have typical primary tuberculous lesions 
and do not have any of the indicators of infectiousness listed 
previously usually do not need to be placed in isolation. Because the 
source case for pediatric TB patients often occurs in a member of the 
infected child's family (45), parents and other visitors of all 
pediatric TB patients should be evaluated for TB as soon as possible.
    Infection is most likely to result from exposure to persons who 
have unsuspected pulmonary TB and are not receiving anti-TB therapy or 
from persons who have diagnosed TB and are not receiving adequate 
therapy. Administration of effective anti-TB therapy has been 
associated with decreased infectiousness among persons who have active 
TB (66). Effective therapy reduces coughing, the amount of sputum 
produced, and the number of organisms in the sputum. However, the 
period of time a patient must take effective therapy before becoming 
noninfectious varies between patients (67). For example, some TB 
patients are never infectious, whereas those with unrecognized or 
inadequately treated drug-resistant TB may remain infectious for weeks 
or months (24). Thus, decisions about infectiousness should be made on 
an individual basis.
    In general, patients who have suspected or confirmed active TB 
should be considered infectious if they (a) are coughing, (b) are 
undergoing cough-inducing procedures, or (c) have positive AFB sputum 
smears, and if they (a) are not on chemotherapy, (b) have just started 
chemotherapy, or (c) have a poor clinical or bacteriologic response to 
chemotherapy. A patient who has drug-susceptible TB and who is on 
adequate chemotherapy and has had a significant clinical and 
bacteriologic response to therapy (i.e., reduction in cough, resolution 
of fever, and progressively decreasing quantity of bacilli on smear) is 
probably no longer infectious. However, because drug-susceptibility 
results are not usually known when the decision to discontinue 
isolation is made, all TB patients should remain in isolation while 
hospitalized until they have had three consecutive negative sputum 
smears collected on different days and they demonstrate clinical 
improvement.

Supplement 2: Diagnosis and Treatment of Latent TB Infection and Active 
TB

I. Diagnostic Procedures for TB Infection and Disease
    A diagnosis of TB may be considered for any patient who has a 
persistent cough (i.e., a cough lasting 3 weeks) or other 
signs or symptoms compatible with TB (e.g., bloody sputum, night 
sweats, weight loss, anorexia, or fever). However, the index of 
suspicion for TB will vary in different geographic areas and will 
depend on the prevalence of TB and other characteristics of the 
population served by the facility. The index of suspicion for TB should 
be very high in areas or among groups of patients in which the 
prevalence of TB is high (Section I.B). Persons for whom a diagnosis of 
TB is being considered should receive appropriate diagnostic tests, 
which may include PPD skin testing, chest radiography, and 
bacteriologic studies (e.g., sputum microscopy and culture).
A. PPD Skin Testing and Anergy Testing
1. Application and Reading of PPD Skin Tests
    The PPD skin test is the only method available for demonstrating 
infection with M. tuberculosis. Although currently available PPD tests 
are <100% sensitive and specific for detection of infection with M. 
tuberculosis, no better diagnostic methods have yet been devised. 
Interpretation of PPD test results requires knowledge of the antigen 
used, the immunologic basis for the reaction to this antigen, the 
technique used to administer and read the test, and the results of 
epidemiologic and clinical experience with the test (2,5,6). The PPD 
test, like all medical tests, is subject to variability, but many of 
the variations in administering and reading PPD tests can be avoided by 
proper training and careful attention to details.
    The intracutaneous (Mantoux) administration of a measured amount of 
PPD-tuberculin is currently the preferred method for doing the test. 
One-tenth milliliter of PPD (5 TU) is injected just beneath the surface 
of the skin on either the volar or dorsal surface of the forearm. A 
discrete, pale elevation of the skin (i.e., a wheal) that is 6-10 mm in 
diameter should be produced.
    PPD test results should be read by designated, trained personnel 
between 48 and 72 hours after injection. Patient or HCW self-reading of 
PPD test results should not be accepted (68). The result of the test is 
based on the presence or absence of an induration at the injection 
site. Redness or erythema should not be measured. The transverse 
diameter of induration should be recorded in millimeters.
2. Interpretation of PPD Skin Tests
    a. General.
    The interpretation of a PPD reaction should be influenced by the 
purpose for which the test was given (e.g., epidemiologic versus 
diagnostic purposes), by the prevalence of TB infection in the 
population being tested, and by the consequences of false 
classification. Errors in classification can be minimized by 
establishing an appropriate definition of a positive reaction (Table 
S2-1).
    The positive-predictive value of PPD tests (i.e, the probability 
that a person with a positive PPD test is actually infected with M. 
tuberculosis) is dependent on the prevalence of TB infection in the 
population being tested and the specificity of the test (69,70). In 
populations with a low prevalence of TB infection, the probability that 
a positive PPD test represents true infection with M. tuberculosis is 
very low if the cut-point is set too low (i.e., the test is not 
adequately specific). In populations with a high prevalence of TB 
infection, the probability that a positive PPD test using the same cut-
point represents true infection with M. tuberculosis is much higher. To 
ensure that few persons infected with tubercle bacilli will be 
misclassified as having negative reactions and few persons not infected 
with tubercle bacilli will be misclassified as having positive 
reactions, different cut-points are used to separate positive reactions 
from negative reactions for different populations, depending on the 
risk for TB infection in that population.
    A lower cut-point (i.e., 5 mm) is used for persons in the highest 
risk groups, which include HIV-infected persons, recent close contacts 
of persons with TB (e.g., in the household or in an unprotected 
occupational exposure similar in intensity and duration to household 
contact), and persons who have abnormal chest radiographs with fibrotic 
changes consistent with inactive TB. A higher cut-point (i.e., 10 mm) 
is used for persons who are not in the highest risk group but who have 
other risk factors (e.g., injecting-drug users known to be HIV 
seronegative; persons with certain medical conditions that increase the 
risk for progression from latent TB infection to active TB [Table S2-
1]); medically underserved, low-income populations; persons born in 
foreign countries that have a high prevalence of TB; and residents of 
correctional institutions and nursing homes). An even higher cut-point 
(i.e., 15 mm) is used for all other persons who have none of the above 
risk factors.
    Recent PPD converters are considered members of a high-risk group. 
A 10 mm increase in the size of the induration within a 2-
year period is classified as a conversion from a negative to a positive 
test result for persons <35 years of age. An increase of induration of 
15 mm within a 2-year period is classified as a conversion 
for persons 35 years of age (5).
    b. HCWs.
    In general, HCWs should have their skin-test results interpreted 
according to the recommendations in this supplement and in sections 1, 
2, 3, and 5 of Table S2-1. However, the prevalence of TB in the 
facility should be considered when choosing the appropriate cut-point 
for defining a positive PPD reaction. In facilities where there is 
essentially no risk for exposure to TB patients (i.e., minimal- or very 
low-risk facilities [Section II.B]), an induration 15 mm may 
be an appropriate cut-point for HCWs who have no other risk factors. In 
other facilities where TB patients receive care, the appropriate cut-
point for HCWs who have no other risk factors may be 10 mm.
    A recent PPD test conversion in an HCW should be defined generally 
as an increase of 10 mm in the size of induration within a 
2-year period. For HCWs in facilities where exposure to TB is very 
unlikely (e.g., minimal-risk facilities), an increase of 15 
mm within a 2-year period may be more appropriate for defining a recent 
conversion because of the lower positive-predictive value of the test 
in such groups.
3. Anergy Testing
    HIV-infected persons may have suppressed reactions to PPD skin 
tests because of anergy, particularly if their CD4+ T-lymphocyte counts 
decline (71). Persons with anergy will have a negative PPD test 
regardless of infection with M. tuberculosis. HIV-infected persons 
should be evaluated for anergy in conjunction with PPD testing (72). 
Two companion antigens (e.g., Candida antigen and tetanus toxoid) 
should be administered in addition to PPD. Persons with 3 mm 
of induration to any of the skin tests (including tuberculin) are 
considered not anergic. Reactions of 5 mm to PPD are 
considered to be evidence of TB infection in HIV-infected persons 
regardless of the reactions to the companion antigens. If there is no 
reaction (i.e., <3 mm induration) to any of the antigens, the person 
being tested is considered anergic. Determination of whether such 
persons are likely to be infected with M. tuberculosis must be based on 
other epidemiologic factors (e.g., the proportion of other persons with 
the same level of exposure who have positive PPD test results and the 
intensity or duration of exposure to infectious TB patients that the 
anergic person experienced).
4. Pregnancy and PPD Skin Testing
    Although thousands (perhaps millions) of pregnant women have been 
PPD skin tested since the test was devised, thus far no documented 
episodes of fetal harm have resulted from use of the tuberculin test 
(73). Pregnancy should not exclude a female HCW from being skin tested 
as part of a contact investigation or as part of a regular skin-testing 
program.

Table S2-1. Summary of Interpretation of Purified Protein Derivative 
(PPD)-Tuberculin Skin-Test Results

    1. An induration of 5 mm is classified as positive in:
     Persons who have human immunodeficiency virus (HIV) 
infection or risk factors for HIV infection but unknown HIV status;
     Persons who have had recent close contact* with persons 
who have active tuberculosis (TB);
---------------------------------------------------------------------------

    *Recent close contact implies either household or social contact 
or unprotected occupational exposure similar in intensity and 
duration to household contact.
---------------------------------------------------------------------------

     Persons who have fibrotic chest radiographs (consistent 
with healed TB).
    2. An induration of 10 mm is classified as positive in 
all persons who do not meet any of the criteria above but who have 
other risk factors for TB, including:

High-Risk Groups

     Injecting-drug users known to be HIV seronegative;
     Persons who have other medical conditions that reportedly 
increase the risk for progressing from latent TB infection to active TB 
(e.g., silicosis; gastrectomy or jejuno-ileal bypass; being 
10% below ideal body weight; chronic renal failure with 
renal dialysis; diabetes mellitus; high-dose corticosteroid or other 
immuno-suppressive therapy; some hematologic disorders, including 
malignancies such as leukemias and lymphomas; and other malignancies);
     Children <4 years of age.

High-prevalence Groups

     Persons born in countries in Asia, Africa, the Caribbean, 
and Latin America that have high prevalence of TB;
     Persons from medically underserved, low-income 
populations;
     Residents of long-term-care facilities (e.g., correctional 
institutions and nursing homes);
     Persons from high-risk populations in their communities, 
as determined by local public health authorities.
    3. An induration of 15 mm is classified as positive in 
persons who do not meet any of the above criteria.
    4. Recent converters are defined on the basis of both size of 
induration and age of the person being tested:
     10 mm increase within a 2-year period is 
classified as a recent conversion for persons <35 years of age;
     15 mm increase within a 2-year period is 
classified as a recent conversion for persons 35 years of 
age.
    5. PPD skin-test results in health-care workers (HCWs)
     In general, the recommendations in sections 1, 2, and 3 of 
this table should be followed when interpreting skin-test results in 
HCWs.
    However, the prevalence of TB in the facility should be considered 
when choosing the appropriate cut-point for defining a positive PPD 
reaction. In facilities where there is essentially no risk for exposure 
to Mycobacterium tuberculosis (i.e., minimal- or very low-risk 
facilities [Section II.B]), an induration 15 mm may be a 
suitable cut-point for HCWs who have no other risk factors. In 
facilities where TB patients receive care, the cut-point for HCWs with 
no other risk factors maybe 10 mm.
     A recent conversion in an HCW should be defined generally 
as a 10 mm increase in size of induration within a 2-year 
period. For HCWs who work in facilities where exposure to TB is very 
unlikely (e.g., minimal-risk facilities), an increase of 15 
mm within a 2-year period may be more appropriate for defining a recent 
conversion because of the lower positive-predictive value of the test 
in such groups.
5. BCG Vaccination and PPD Skin Testing
    BCG vaccination may produce a PPD reaction that cannot be 
distinguished reliably from a reaction caused by infection with M. 
tuberculosis. For a person who was vaccinated with BCG, the probability 
that a PPD test reaction results from infection with M. tuberculosis 
increases (a) as the size of the reaction increases, (b) when the 
person is a contact of a person with TB, (c) when the person's country 
of origin has a high prevalence of TB, and (d) as the length of time 
between vaccination and PPD testing increases. For example, a PPD test 
reaction of 10 mm probably can be attributed to M. 
tuberculosis infection in an adult who was vaccinated with BCG as a 
child and who is from a country with a high prevalence of TB (74,75).
6. The Booster Phenomenon
    The ability of persons who have TB infection to react to PPD may 
gradually wane. For example, if tested with PPD, adults who were 
infected during their childhood may have a negative reaction. However, 
the PPD could boost the hypersensitivity, and the size of the reaction 
could be larger on a subsequent test. This boosted reaction may be 
misinterpreted as a PPD test conversion from a newly acquired 
infection. Misinterpretation of a boosted reaction as a new infection 
could result in unnecessary investigations of laboratory and patient 
records in an attempt to identify the source case and in unnecessary 
prescription of preventive therapy for HCWs. Although boosting can 
occur among persons in any age group, the likelihood of the reaction 
increases with the age of the person being tested (6,76).
    When PPD testing of adults is to be repeated periodically (as in 
HCW skin-testing programs), two-step testing can be used to reduce the 
likelihood that a boosted reaction is misinterpreted as a new 
infection. Two-step testing should be performed on all newly employed 
HCWs who have an initial negative PPD test result at the time of 
employment and have not had a documented negative PPD test result 
during the 12 months preceding the initial test. A second test should 
be performed 1-3 weeks after the first test. If the second test result 
is positive, this is most likely a boosted reaction, and the HCW should 
be classified as previously infected. If the second test result remains 
negative, the HCW is classified as uninfected, and a positive reaction 
to a subsequent test is likely to represent a new infection with M. 
tuberculosis.
B. Chest Radiography
    Patients who have positive skin-test results or symptoms suggestive 
of TB should be evaluated with a chest radiograph regardless of PPD 
test results. Radiographic abnormalities that strongly suggest active 
TB include upper-lobe infiltration, particularly if cavitation is seen 
(77), and patchy or nodular infiltrates in the apical or subapical 
posterior upper lobes or the superior segment of the lower lobe. If 
abnormalities are noted, or if the patient has symptoms suggestive of 
extrapulmonary TB, additional diagnostic tests should be conducted.
    The radiographic presentation of pulmonary TB in HIV-infected 
patients may be unusual (78). Typical apical cavitary disease is less 
common among such patients. They may have infiltrates in any lung zone, 
a finding that is often associated with mediastinal and/or hilar 
adenopathy, or they may have a normal chest radiograph, although this 
latter finding occurs rarely.
C. Bacteriology
    Smear and culture examination of at least three sputum specimens 
collected on different days is the main diagnostic procedure for 
pulmonary TB (6). Sputum smears that fail to demonstrate AFB do not 
exclude the diagnosis of TB. In the United States, approximately 60% of 
patients with positive sputum cultures have positive AFB sputum smears. 
HIV-infected patients who have pulmonary TB may be less likely than 
immunocompetent patients to have AFB present on sputum smears, which is 
consistent with the lower frequency of cavitary pulmonary disease 
observed among HIV-infected persons (39,41).
    Specimens for smear and culture should contain an adequate amount 
of expectorated sputum but not much saliva. If a diagnosis of TB cannot 
be established from sputum, a bronchoscopy may be necessary (36,37). In 
young children who cannot produce an adequate amount of sputum, gastric 
aspirates may provide an adequate specimen for diagnosis.
    A culture of sputum or other clinical specimen that contains M. 
tuberculosis provides a definitive diagnosis of TB. Conventional 
laboratory methods may require 4-8 weeks for species identification; 
however, the use of radiometric culture techniques and nucleic acid 
probes facilitates more rapid detection and identification of 
mycobacteria (79,80). Mixed mycobacterial infection, either 
simultaneous or sequential, can obscure the identification of M. 
tuberculosis during the clinical evaluation and the laboratory analysis 
(42). The use of nucleic acid probes for both M. avium complex and M. 
tuberculosis may be useful for identifying mixed mycobacterial 
infections in clinical specimens.

II. Preventive Therapy for Latent TB Infection and Treatment of Active 
TB

A. Preventive Therapy for Latent TB Infection
    Determining whether a person with a positive PPD test reaction or 
conversion is a candidate for preventive therapy must be based on (a) 
the likelihood that the reaction represents true infection with M. 
tuberculosis (as determined by the cut-points), (b) the estimated risk 
for progression from latent infection to active TB, and (c) the risk 
for hepatitis associated with taking isoniazid (INH) preventive therapy 
(as determined by age and other factors).
    HCWs with positive PPD test results should be evaluated for 
preventive therapy regardless of their ages if they (a) are recent 
converters, (b) are close contacts of persons who have active TB, (c) 
have a medical condition that increases the risk for TB, (d) have HIV 
infection, or (e) use injecting drugs (5). HCWs with positive PPD test 
results who do not have these risk factors should be evaluated for 
preventive therapy if they are <35 years of age.
    Preventive therapy should be considered for anergic persons who are 
known contacts of infectious TB patients and for persons from 
populations in which the prevalence of TB infection is very high (e.g., 
a prevalence of >10%).
    Because the risk for INH-associated hepatitis may be increased 
during the peripartum period, the decision to use preventive therapy 
during pregnancy should be made on an individual basis and should 
depend on the patient's estimated risk for progression to active 
disease. In general, preventive therapy can be delayed until after 
delivery. However, for pregnant women who were probably infected 
recently or who have high-risk medical conditions, especially HIV 
infection, INH preventive therapy should begin when the infection is 
documented (81-84). No evidence suggests that INH poses a carcinogenic 
risk to humans (85-87).
    The usual preventive therapy regimen is oral INH 300 mg daily for 
adults and 10 mg/kg/day for children (88). The recommended duration of 
therapy is 12 months for persons with HIV infection and 9 months for 
children. Other persons should receive INH therapy for 6-12 months. For 
persons who have silicosis or a chest radiograph demonstrating inactive 
fibrotic lesions and who have no evidence of active TB, acceptable 
regimens include (a) 4 months of INH plus rifampin or (b) 12 months of 
INH, providing that infection with INH-resistant organisms is unlikely 
(33). For persons likely to be infected with MDR-TB, alternative 
multidrug preventive therapy regimens should be considered (89).
    All persons placed on preventive therapy should be educated 
regarding the possible adverse reactions associated with INH use, and 
they should be questioned carefully at monthly intervals by qualified 
personnel for signs or symptoms consistent with liver damage or other 
adverse effects (81-84,88,90,91). Because INH-associated hepatitis 
occurs more frequently among persons >35 years of age, a transaminase 
measurement should be obtained from persons in this age group before 
initiation of INH therapy and then obtained monthly until treatment has 
been completed. Other factors associated with an increased risk for 
hepatitis include daily alcohol use, chronic liver disease, and 
injecting-drug use. In addition, postpubertal black and Hispanic women 
may be at greater risk for hepatitis or drug interactions (92). More 
careful clinical monitoring of persons with these risk factors and 
possibly more frequent laboratory monitoring should be considered. If 
any of these tests exceeds three to five times the upper limit of 
normal, discontinuation of INH should be strongly considered. Liver 
function tests are not a substitute for monthly clinical evaluations or 
for the prompt assessment of signs or symptoms of adverse reactions 
that could occur between the regularly scheduled evaluations (33).
    Persons who have latent TB infection should be advised that they 
can be reinfected with another strain of M. tuberculosis (93).
B. Treatment of Patients Who Have Active TB
    Drug-susceptibility testing should be performed on all initial 
isolates from patients with TB. However, test results may not be 
available for several weeks, making selection of an initial regimen 
difficult, especially in areas where drug-resistant TB has been 
documented. Current recommendations for therapy and dosage schedules 
for the treatment of drug-susceptible TB should be followed (Table S2-
2; Table S2-3) (43). Streptomycin is contraindicated in the treatment 
of pregnant women because of the risk for ototoxicity to the fetus. In 
geographic areas or facilities in which drug-resistant TB is highly 
prevalent, the initial treatment regimen used while results of drug-
susceptibility tests are pending may need to be expanded. This decision 
should be based on analysis of surveillance data.
    When results from drug-susceptibility tests become available, the 
regimen should be adjusted appropriately (94-97). If drug resistance is 
present, clinicians unfamiliar with the management of patients with 
drug-resistant TB should seek expert consultation.
    For any regimen to be effective, adherence to the regimen must be 
ensured. The most effective method of ensuring adherence is the use of 
DOT after the patient has been discharged from the hospital (43,91). 
This practice should be coordinated with the public health department.

                               Table S2-2.--Regimen Options for the Treatment of Tuberculosis (TB) in Children and Adults                               
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Initial treatment phase            Continuation treatment phase                                
                                          Total    ---------------------------------------------------------------------------                          
  Option           Indication          duration of                      Interval and                                                    Comments        
                                         therapy         Drugs*           duration        Drugs*       Interval and duration                            
--------------------------------------------------------------------------------------------------------------------------------------------------------
1........  Pulmonary and              6 mos.......  INH.............  Daily for 8 wks  INH.........  Daily or two or three     EMB or SM should 
            extrapulmonary TB in                    RIF                                RIF            times wkly for    be continued until      
            adults and children.                    PZA                                               16 wksSec. .              susceptibility to INH   
                                                    EMB or SM                                                                   and RIF is demonstrated.
                                                                                                                               In areas where   
                                                                                                                                primary INH resistance  
                                                                                                                                is <4%, EMB or SM may   
                                                                                                                                not be necessary for    
                                                                                                                                patients with no        
                                                                                                                                individual risk factors 
                                                                                                                                for drug resistance.    
2........  Pulmonary and              6 mos.......  INH.............  Daily for 2      INH.........  Two times wkly    Regimen should be
            extrapulmonary TB in                    RIF                wks, then two   RIF            for 16 wksSec. .          directly observed.      
            adults and children.                    PZA                times                                                   After the initial
                                                    EMB or SM          wkly                                             phase, EMB or SM should 
                                                                       for 6 wks.                                               be continued until      
                                                                                                                                susceptibility to INH   
                                                                                                                                and RIF is demonstrated,
                                                                                                                                unless drug resistance  
                                                                                                                                is unlikely.            
3........  Pulmonary and              6 mos.......  INH.............                                                                                    
            extrapulmonary TB in                    RIF                                                                                                 
            adults and children.                    PZA                                                                                                 
                                                    EMB or SM                                                                                           
(2)3       Regimen should be                                                                                                                    
 times      directly observed..                                                                                                                         
 wklyContinue all four                                                                                                                    
 g for 6    drugs for 6 mos..                                                                                                                          
 mosSec.   This regimen has                                                                                                                     
            been shown to be                                                                                                                            
            effective for INH-                                                                                                                          
            resistant TB..                                                                                                                              
4........  Smear- and culture-        4 mos.......  INH.............  Follow option    INH.........  Daily or two or three     Continue all four
            negative pulmonary TB in                RIF                1, 2, or 3 for  RIF            times wkly for    drugs for 4 mos.        
            adults.                                 PZA                8 wks.          PZA            8 wks.                   If drug          
                                                    EMB or SM                          EMB or SM                                resistance is unlikely  
                                                                                                                                (primary INH resistance 
                                                                                                                                <4% and patient has no  
                                                                                                                                individual risk factors 
                                                                                                                                for drug resistance),   
                                                                                                                                EMB or SM may not be    
                                                                                                                                necessary and PZA may be
                                                                                                                                discontinued after 2    
                                                                                                                                mos.                    
5........  Pulmonary and              9 mos.......  INH.............  Daily for 8 wks  INH.........  Daily or two times        EMB or SM should 
            extrapulmonary TB in                    RIF                                RIF            wkly for 24       be continued until      
            adults and children when                EMB or                                            wksSec. .                 susceptibility to INH   
            PZA is contraindicated.                 SM**                                                                        and RIF is demonstrated.
                                                                                                                               In areas where   
                                                                                                                                primary INH resistance  
                                                                                                                                is <4%, EMB or SM may   
                                                                                                                                not be necessary for    
                                                                                                                                patients with no        
                                                                                                                                individual risk factors 
                                                                                                                                for drug resistance.    
--------------------------------------------------------------------------------------------------------------------------------------------------------
*EMB=ethambutol; INH=isoniazid; PZA=pyrazinamide; RIF=rifampin; SM=streptomycin.                                                                        
All regimens administered intermittently should be directly observed.                                                                           
Sec. For infants and children with miliary TB, bone and joint TB, or TB meningitis, treatment should last at least 12 months. For adults with these     
  forms of extrapulmonary TB, response to therapy should be monitored closely. If response is slow or suboptimal, treatment may be prolonged on a case- 
  by-case basis.                                                                                                                                        
Some evidence suggests that SM may be discontinued after 4 months if the isolate is susceptible to all drugs.                                          
**Avoid treating pregnant women with SM because of the risk of ototoxicity to the fetus.                                                                
                                                                                                                                                        
Note: For all patients, if drug-susceptibility results show resistance to any of the first-line drugs, or if the patient remains symptomatic or smear-  
  or culture-positive after 3 months, consult a TB medical expert.                                                                                      


                          Table S2-3.--Dosage Recommendations for the Initial Treatment of Tuberculosis in Children* and Adults                         
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Dosage schedule                                                         
                     -----------------------------------------------------------------------------------------------------------------------------------
        Drug                   Daily dose (maximum dose)               Two doses per week (maximum dose)          Three doses per week (maximum dose)   
                     -----------------------------------------------------------------------------------------------------------------------------------
                            Children               Adults               Children               Adults               Children               Adults       
--------------------------------------------------------------------------------------------------------------------------------------------------------
Isoniazid...........  10-20 mg/kg (300 mg)  5 mg/kg (300 mg)....  20-40 mg/kg (900 mg)  15 mg/kg (900 mg)...  20-40 mg/kg (900 mg)  15 mg/kg) (900 mg)  
Rifampin............  10-20 mg/kg (600 mg)  10 mg/kg (600 mg)...  10-20 mg/kg (600 mg)  10 mg/kg (600 mg)...  10-20 mg/kg (600 mg)  10 mg/kg (600 mg)   
Pyrazinamide........  15-30 mg/kg (2 gm)..  15-30 mg/kg (2 gm)..  50-70 mg/kg (4 gm)..  50-70 mg/kg (4 gm)..  50-70 mg/kg (3 gm)..  50-70 mg/kg (3 gm)  
Ethambutol..........  15-25 mg/kg.........  15-25 mg/kg.........  50 mg/kg............  50 mg/kg............  25-40 mg/kg.........  25-30 mg/kg         
Streptomycin........  20-40 mg/kg (1 gm)..  15 mg/kg (1 gm).....  20-40 mg/kg (1.5 gm)  20-40 mg/kg (1.5 gm)  20-40 mg/kg (1.5 gm)  20-40 mg/kg (1.5 gm)
--------------------------------------------------------------------------------------------------------------------------------------------------------
*Persons 12 years of age.                                                                                                                    

Supplement 3: Engineering Controls

I. Introduction
    This supplement provides information regarding the use of 
ventilation (Section II) and UVGI (Section III) for preventing the 
transmission of M. tuberculosis in health-care facilities. The 
information provided is primarily conceptual and is intended to educate 
staff in the health-care facility concerning engineering controls and 
how these controls can be used as part of the TB infection-control 
program. This supplement should not be used in place of consultation 
with experts, who can assume responsibility for advising on ventilation 
system design and selection, installation, and maintenance of 
equipment.
    The recommendations for engineering controls include (a) local 
exhaust ventilation (i.e., source control), (b) general ventilation, 
and (c) air cleaning. General ventilation considerations include (a) 
dilution and removal of contaminants, (b) airflow patterns within 
rooms, (c) airflow direction in facilities, (d) negative pressure in 
rooms, and (e) TB isolation rooms. Air cleaning or disinfection can be 
accomplished by filtration of air (e.g., through HEPA filters) or by 
UVGI.
II. Ventilation
    Ventilation systems for health-care facilities should be designed, 
and modified when necessary, by ventilation engineers in collaboration 
with infection-control and occupational health staff. Recommendations 
for designing and operating ventilation systems have been published by 
ASHRAE (47), AIA (48), and the American Conference of Governmental 
Industrial Hygienists, Inc. (98).
    As part of the TB infection-control plan, health-care facility 
personnel should determine the number of TB isolation rooms, treatment 
rooms, and local exhaust devices (i.e., for cough-inducing or aerosol-
generating procedures) that the facility needs. The locations of these 
rooms and devices will depend on where in the facility the ventilation 
conditions recommended in this document can be achieved. Grouping 
isolation rooms together in one area of the facility may facilitate the 
care of TB patients and the installation and maintenance of optimal 
engineering controls (particularly ventilation).
    Periodic evaluations of the ventilation system should review the 
number of TB isolation rooms, treatment rooms, and local exhaust 
devices needed and the regular maintenance and monitoring of the local 
and general exhaust systems (including HEPA filtration systems if they 
are used).
    The various types and conditions of ventilation systems in health-
care facilities and the individual needs of these facilities preclude 
the ability to provide specific instructions regarding the 
implementation of these recommendations. Engineering control methods 
must be tailored to each facility on the basis of need and the 
feasibility of using the ventilation and air-cleaning concepts 
discussed in this supplement.
A. Local Exhaust Ventilation
    Purpose: To capture airborne contaminants at or near their source 
(i.e., the source control method) and remove these contaminants without 
exposing persons in the area to infectious agents (98).
    Source control techniques can prevent or reduce the spread of 
infectious droplet nuclei into the general air circulation by 
entrapping infectious droplet nuclei as they are being emitted by the 
patient (i.e., the source). These techniques are especially important 
when performing procedures likely to generate aerosols containing 
infectious particles and when infectious TB patients are coughing or 
sneezing.
    Local exhaust ventilation is a preferred source control technique, 
and it is often the most efficient way to contain airborne contaminants 
because it captures these contaminants near their source before they 
can disperse. Therefore, the technique should be used, if feasible, 
wherever aerosol-generating procedures are performed. Two basic types 
of local exhaust devices use hoods: (a) The enclosing type, in which 
the hood either partially or fully encloses the infectious source; and 
(b) the exterior type, in which the infectious source is near but 
outside the hood. Fully enclosed hoods, booths, or tents are always 
preferable to exterior types because of their superior ability to 
prevent contaminants from escaping into the HCW's breathing zone. 
Descriptions of both enclosing and exterior devices have been published 
previously (98).
1. Enclosing Devices
    The enclosing type of local exhaust ventilation device includes 
laboratory hoods used for processing specimens that could contain 
viable infectious organisms, booths used for sputum induction or 
administration of aerosolized medications (e.g., aerosolized 
pentamidine) (Figure S3-1), and tents or hoods made of vinyl or other 
materials used to enclose and isolate a patient. These devices are 
available in various configurations. The most simple of these latter 
devices is a tent that is placed over the patient; the tent has an 
exhaust connection to the room discharge exhaust system. The most 
complex device is an enclosure that has a sophisticated self-contained 
airflow and recirculation system.
    Both tents and booths should have sufficient airflow to remove at 
least 99% of airborne particles during the interval between the 
departure of one patient and the arrival of the next (99). The time 
required for removing a given percentage of airborne particles from an 
enclosed space depends on several factors. These factors include the 
number of ACH, which is determined by the number of cubic feet of air 
in the room or booth and the rate at which air is entering the room or 
booth at the intake source; the location of the ventilation inlet and 
outlet; and the physical configuration of the room or booth (Table S3-
1).

TN28OC94.004

2. Exterior Devices
    The exterior type of local exhaust ventilation device is usually a 
hood very near, but not enclosing, the infectious patient. The airflow 
produced by these devices should be sufficient to prevent cross-
currents of air near the patient's face from causing escape of droplet 
nuclei. Whenever possible, the patient should face directly into the 
hood opening so that any coughing or sneezing is directed into the 
hood, where the droplet nuclei are captured. The device should maintain 
an air velocity of  200 feet per minute at the patient's 
breathing zone to ensure capture of droplet nuclei.
3. Discharge Exhaust From Booths, Tents, and Hoods
    Air from booths, tents, and hoods may be discharged into the room 
in which the device is located or it may be exhausted to the outside. 
If the air is discharged into the room, a HEPA filter should be 
incorporated at the discharge duct or vent of the device. The exhaust 
fan should be located on the discharge side of the HEPA filter to 
ensure that the air pressure in the filter housing and booth is 
negative with respect to adjacent areas. Uncontaminated air from the 
room will flow into the booth through all openings, thus preventing 
infectious droplet nuclei in the booth from escaping into the room. 
Most commercially available booths, tents, and hoods are fitted with 
HEPA filters, in which case additional HEPA filtration is not needed.
    If the device does not incorporate a HEPA filter, the air from the 
device should be exhausted to the outside in accordance with 
recommendations for isolation room exhaust (Suppl. 3, Section II.B.5). 
(See Supplement 3, Section II.C, for information regarding 
recirculation of exhaust air.)

Table S3-1.--Air Changes Per Hour (ACH) and Time in Minutes Required for
  Removal Efficiencies of 90%, 99%, and 99.9% of Airborne Contaminants* 
------------------------------------------------------------------------
                                                 Minutes required for a 
                                                 removal efficiency of: 
                     ACH                      --------------------------
                                                 90%      99%     99.9% 
------------------------------------------------------------------------
1............................................      138      276      414
2............................................       69      138      207
3............................................       46       92      138
4............................................       35       69      104
5............................................       28       55       83
6............................................       23       46       69
7............................................       20       39       59
8............................................       17       35       52
9............................................       15       31       46
10...........................................       14       28       41
11...........................................       13       25       38
12...........................................       12       23       35
13...........................................       11       21       32
14...........................................       10       20       30
15...........................................        9       18       28
16...........................................        9       17       26
17...........................................        8       16       24
18...........................................        8       15       23
19...........................................        7       15       22
20...........................................        7       14       21
25...........................................        6       11       17
30...........................................        5        9       14
35...........................................        4        8       12
40...........................................        3        7       10
45...........................................        3        6        9
50...........................................        3        6       8 
------------------------------------------------------------------------
*This table has been adapted from the formula for the rate of purging   
  airborne contaminants (99). Values have been derived from the formula 
  t1 = [In C2  C1)  (Q  V)]  x  60, with T1 = 0 
  and C2  C1 - (removal efficiency  100), and where:    
t1 = initial timepoint                                                  
C1 = initial concentration of contaminant                               
C2 = final concentration of contaminants                                
Q = air flow rate (cubic feet per hour)                                 
V = room volume (cubic feet)                                            
Q  V = ACH                                                      
The times given assume perfect mixing of the air within the space (i.e.,
  mixing factor = 1). However, perfect mixing usually does not occur,   
  and the mixing factor could be as high as 10 if air distribution is   
  very poor (98). The required time is derived by multiplying the       
  appropriate time from the table by the mixing factor that has been    
  determined for the booth or room. The factor and required time should 
  be included in the operating instructions provided by the manufacturer
  of the booth or enclosure, and these instructions should be followed. 

B. General Ventilation
    General ventilation can be used for several purposes, including 
diluting and removing contaminated air, controlling airflow patterns 
within rooms, and controlling the direction of airflow throughout a 
facility. Information on these topics is contained in the following 
sections.
1. Dilution and Removal
    Purpose: To reduce the concentration of contaminants in the air.
    General ventilation maintains air quality by two processes: 
dilution and removal of airborne contaminants. Uncontaminated supply 
(i.e., incoming) air mixes with the contaminated room air (i.e., 
dilution), which is subsequently removed from the room by the exhaust 
system (i.e., removal). These processes reduce the concentration of 
droplet nuclei in the room air.
    a. Types of general ventilation systems.
    Two types of general ventilation systems can be used for dilution 
and removal of contaminated air: the single-pass system and the 
recirculating system. In a single-pass system, the supply air is either 
outside air that has been appropriately heated and cooled or air from a 
central system that supplies a number of areas. After air passes 
through the room (or area), 100% of that air is exhausted to the 
outside. The single-pass system is the preferred choice in areas where 
infectious airborne droplet nuclei are known to be present (e.g., TB 
isolation rooms or treatment rooms) because it prevents contaminated 
air from being recirculated to other areas of the facility.
    In a recirculating system, a small portion of the exhaust air is 
discharged to the outside and is replaced with fresh outside air, which 
mixes with the portion of exhaust air that was not discharged to the 
outside. The resulting mixture, which can contain a large proportion of 
contaminated air, is then recirculated to the areas serviced by the 
system. This air mixture could be recirculated into the general 
ventilation, in which case contaminants may be carried from 
contaminated areas to uncontaminated areas. Alternatively, the air 
mixture could also be recirculated within a specific room or area, in 
which case other areas of the facility will not be affected (Suppl. 3, 
Section II.C.3).
    b. Ventilation rates.
    Recommended general ventilation rates for health-care facilities 
are usually expressed in number of ACH. This number is the ratio of the 
volume of air entering the room per hour to the room volume and is 
equal to the exhaust airflow (Q [cubic feet per minute]) divided by the 
room volume (V [cubic feet]) multiplied by 60 (i.e., ACH = Q  V 
 x  60).
    The feasibility of achieving specific ventilation rates depends on 
the construction and operational requirements of the ventilation system 
(e.g., the energy requirements to move and to heat or cool the air). 
The feasibility of achieving specific ventilation rates may also be 
different for retrofitted facilities and newly constructed facilities. 
The expense and effort of achieving specific higher ventilation rates 
for new construction may be reasonable, whereas retrofitting an 
existing facility to achieve similar ventilation rates may be more 
difficult. However, achieving higher ventilation rates by using 
auxiliary methods (e.g., room-air recirculation) in addition to exhaust 
ventilation may be feasible in existing facilities (Suppl. 3, Section 
II.C).
2. Airflow Patterns Within Rooms (Air Mixing)
    Purpose: To provide optimum airflow patterns and prevent both 
stagnation and short-circuiting of air.
    General ventilation systems should be designed to provide optimal 
patterns of airflow within rooms and prevent air stagnation or short-
circuiting of air from the supply to the exhaust (i.e., passage of air 
directly from the air supply to the air exhaust). To provide optimal 
airflow patterns, the air supply and exhaust should be located such 
that clean air first flows to parts of the room where HCWs are likely 
to work, and then flows across the infectious source and into the 
exhaust. In this way, the HCW is not positioned between the infectious 
source and the exhaust location. Although this configuration may not 
always be possible, it should be used whenever feasible. One way to 
achieve this airflow pattern is to supply air at the side of the room 
opposite the patient and exhaust it from the side where the patient is 
located. Another method, which is most effective when the supply air is 
cooler than the room air, is to supply air near the ceiling and exhaust 
it near the floor (Figure S3-2). Airflow patterns are affected by large 
air temperature differentials, the precise location of the supply and 
exhausts, the location of furniture, the movement of HCWs and patients, 
and the physical configuration of the space. Smoke tubes can be used to 
visualize airflow patterns in a manner similar to that described for 
estimating room air mixing.

TN28OC94.005

      
    Adequate air mixing, which requires that an adequate number of ACH 
be provided to a room (Suppl. 3, Section II.B.1), must be ensured to 
prevent air stagnation within the room. However, the air will not 
usually be changed the calculated number of times per hour because the 
airflow patterns in the room may not permit complete mixing of the 
supply and room air in all parts of the room. This results in an 
``effective'' airflow rate in which the supplied airflow may be less 
than required for proper ventilation. To account for this variation, a 
mixing factor (which ranges from 1 for perfect mixing to 10 for poor 
mixing) is applied as a multiplier to determine the actual supply 
airflow (i.e., the recommended ACH multiplied by the mixing factor 
equals the actual required ACH) (51,98). The room air supply and 
exhaust system should be designed to achieve the lowest mixing factor 
possible. The mixing factor is determined most accurately by 
experimentally testing each space configuration, but this procedure is 
complex and time-consuming. A reasonably good qualitative measure of 
mixing can be estimated by an experienced ventilation engineer who 
releases smoke from smoke tubes at a number of locations in the room 
and observes the movement of the smoke. Smoke movement in all areas of 
the room indicates good mixing. Stagnation of air in some areas of the 
room indicates poor mixing, and movement of the supply and exhaust 
openings or redirection of the supply air is necessary.
3. Airflow Direction in the Facility
    Purpose: To contain contaminated air in localized areas in a 
facility and prevent its spread to uncontaminated areas.
    a. Directional airflow.
    The general ventilation system should be designed and balanced so 
that air flows from less contaminated (i.e., more clean) to more 
contaminated (less clean) areas (47,48). For example, air should flow 
from corridors (cleaner areas) into TB isolation rooms (less clean 
areas) to prevent spread of contaminants to other areas. In some 
special treatment rooms in which operative and invasive procedures are 
performed, the direction of airflow is from the room to the hallway to 
provide cleaner air during these procedures. Cough-inducing or aerosol-
generating procedures (e.g., bronchoscopy and irrigation of tuberculous 
abscesses) should not be performed in rooms with this type of airflow 
on patients who may have infectious TB.
    b. Negative pressure for achieving directional airflow.
    The direction of airflow is controlled by creating a lower 
(negative) pressure in the area into which the flow of air is desired. 
For air to flow from one area to another, the air pressure in the two 
areas must be different. Air will flow from a higher pressure area to a 
lower pressure area. The lower pressure area is described as being at 
negative* pressure relative to the higher pressure area. Negative 
pressure is attained by exhausting air from an area at a higher rate 
than air is being supplied. The level of negative pressure necessary to 
achieve the desired airflow will depend on the physical configuration 
of the ventilation system and area, including the airflow path and flow 
openings, and should be determined on an individual basis by an 
experienced ventilation engineer.
---------------------------------------------------------------------------

    *Negative is defined relative to the air pressure in the area 
from which air is to flow.
---------------------------------------------------------------------------

4. Achieving Negative Pressure in a Room
    Purpose: To control the direction of airflow between the room and 
adjacent areas, thereby preventing contaminated air from escaping from 
the room into other areas of the facility.
    a. Pressure differential.
    The minimum pressure difference necessary to achieve and maintain 
negative pressure that will result in airflow into the room is very 
small (0.001 inch of water). Higher pressures ( 0.001 inch 
of water) are satisfactory; however, these higher pressures may be 
difficult to achieve. The actual level of negative pressure achieved 
will depend on the difference in the ventilation exhaust and supply 
flows and the physical configuration of the room, including the airflow 
path and flow openings. If the room is well sealed, negative pressures 
greater than the minimum of 0.001 inch of water may be readily 
achieved. However, if rooms are not well sealed, as may be the case in 
many facilities (especially older facilities), achieving higher 
negative pressures may require exhaust/supply flow differentials beyond 
the capability of the ventilation system.
    To establish negative pressure in a room that has a normally 
functioning ventilation system, the room supply and exhaust airflows 
are first balanced to achieve an exhaust flow of either 10% or 50 cubic 
feet per minute (cfm) greater than the supply (whichever is the 
greater). In most situations, this specification should achieve a 
negative pressure of at least 0.001 inch of water. If the minimum 0.001 
inch of water is not achieved and cannot be achieved by increasing the 
flow differential (within the limits of the ventilation system), the 
room should be inspected for leakage (e.g., through doors, windows, 
plumbing, and equipment wall penetrations), and corrective action 
should be taken to seal the leaks.
    Negative pressure in a room can be altered by changing the 
ventilation system operation or by the opening and closing of the 
room's doors, corridor doors, or windows. When an operating 
configuration has been established, it is essential that all doors and 
windows remain properly closed in the isolation room and other areas 
(e.g., doors in corridors that affect air pressure) except when persons 
need to enter or leave the room or area.
    b. Alternate methods for achieving negative pressure.
    Although an anteroom is not a substitute for negative pressure in a 
room, it may be used to reduce escape of droplet nuclei during opening 
and closing of the isolation room door. Some anterooms have their own 
air supply duct, but others do not. The TB isolation room should have 
negative pressure relative to the anteroom, but the air pressure in the 
anteroom relative to the corridor may vary depending on the building 
design. This should be determined, in accordance with applicable 
regulations, by a qualified ventilation engineer.
    If the existing ventilation system is incapable of achieving the 
desired negative pressure because the room lacks a separate ventilation 
system or the room's system cannot provide the proper airflow, steps 
should be taken to provide a means to discharge air from the room. The 
amount of air to be exhausted will be the same as discussed previously 
(Suppl. 3, Section II.B.4.a).
    Fixed room-air recirculation systems (i.e., systems that 
recirculate the air in an entire room) may be designed to achieve 
negative pressure by discharging air outside the room (Suppl. 3, 
Section II.C.3).
    Some portable room-air recirculation units (Suppl. 3, Section 
II.C.3.b.) are designed to discharge air to the outside to achieve 
negative pressure. Air cleaners that can accomplish this must be 
designed specifically for this purpose.
    A small centrifugal blower (i.e., exhaust fan) can be used to 
exhaust air to the outside through a window or outside wall. This 
approach may be used as an interim measure to achieve negative 
pressure, but it provides no fresh air and suboptimal dilution.
    Another approach to achieving the required pressure difference is 
to pressurize the corridor. Using this method, the corridor's general 
ventilation system is balanced to create a higher air pressure in the 
corridor than in the isolation room; the type of balancing necessary 
depends on the configuration of the ventilation system. Ideally, the 
corridor air supply rate should be increased while the corridor exhaust 
rate is not increased. If this is not possible, the exhaust rate should 
be decreased by resetting appropriate exhaust dampers. Caution should 
be exercised, however, to ensure that the exhaust rate is not reduced 
below acceptable levels. This approach requires that all settings used 
to achieve the pressure balance, including doors, be maintained. This 
method may not be desirable if the corridor being pressurized has rooms 
in which negative pressure is not desired. In many situations, this 
system is difficult to achieve, and it should be considered only after 
careful review by ventilation personnel.
    c. Monitoring negative pressure.
    The negative pressure in a room can be monitored by visually 
observing the direction of airflow (e.g., using smoke tubes) or by 
measuring the differential pressure between the room and its 
surrounding area.
    Smoke from a smoke tube can be used to observe airflow between 
areas or airflow patterns within an area. To check the negative 
pressure in a room by using a smoke tube, hold the smoke tube near the 
bottom of the door and approximately 2 inches in front of the door, or 
at the face of a grille or other opening if the door has such a 
feature, and generate a small amount of smoke by gently squeezing the 
bulb (Figure S3-3). The smoke tube should be held parallel to the door, 
and the smoke should be issued from the tube slowly to ensure the 
velocity of the smoke from the tube does not overpower the air 
velocity. The smoke will travel in the direction of airflow. If the 
room is at negative pressure, the smoke will travel under the door and 
into the room (e.g., from higher to lower pressure). If the room is not 
at negative pressure, the smoke will be blown outward or will stay 
stationary. This test must be performed while the door is closed. If 
room air cleaners are being used in the room, they should be running. 
The smoke is irritating if inhaled, and care should be taken not to 
inhale it directly from the smoke tube. However, the quantity of smoke 
issued from the tube is minimal and is not detectable at short 
distances from the tube.
    Differential pressure-sensing devices also can be used to monitor 
negative pressure; they can provide either periodic (noncontinuous) 
pressure measurements or continuous pressure monitoring. The continuous 
monitoring component may simply be a visible and/or audible warning 
signal that air pressure is low. In addition, it may also provide a 
pressure readout signal, which can be recorded for later verification 
or used to automatically adjust the facility's ventilation control 
system.

TN28OC94.006

    Pressure-measuring devices should sense the room pressure just 
inside the airflow path into the room (e.g., at the bottom of the 
door). Unusual airflow patterns within the room can cause pressure 
variations; for example, the air can be at negative pressure at the 
middle of a door and at positive pressure at the bottom of the same 
door (Figure S3-4). If the pressure-sensing ports of the device cannot 
be located directly across the airflow path, it will be necessary to 
validate that the negative pressure at the sensing point is and remains 
the same as the negative pressure across the flow path.
    Pressure-sensing devices should incorporate an audible warning with 
a time delay to indicate that a door is open. When the door to the room 
is opened, the negative pressure will decrease. The time-delayed signal 
should allow sufficient time for persons to enter or leave the room 
without activating the audible warning.

TN28OC94.007

    A potential problem with using pressure-sensing devices is that the 
pressure differentials used to achieve the low negative pressure 
necessitate the use of very sensitive mechanical devices, electronic 
devices, or pressure gauges to ensure accurate measurements. Use of 
devices that cannot measure these low pressures (i.e., pressures as low 
as 0.001 inch of water) will require setting higher negative pressures 
that may be difficult and, in some instances, impractical to achieve 
(Suppl. 3, Section II.B.4).
    Periodic checks are required to ensure that the desired negative 
pressure is present and that the continuous monitoring devices, if 
used, are operating properly. If smoke tubes or other visual checks are 
used, TB isolation rooms and treatment rooms should be checked 
frequently for negative pressure. Rooms undergoing changes to the 
ventilation system should be checked daily. TB isolation rooms should 
be checked daily for negative pressure while being used for TB 
isolation. If these rooms are not being used for patients who have 
suspected or confirmed TB but potentially could be used for such 
patients, the negative pressure in the rooms should be checked monthly. 
If pressure-sensing devices are used, negative pressure should be 
verified at least once a month by using smoke tubes or taking pressure 
measurements.
C. HEPA Filtration
    Purpose: To remove contaminants from the air.
    HEPA filtration can be used as a method of air cleaning that 
supplements other recommended ventilation measures. For the purposes of 
these guidelines, HEPA filters are defined as air-cleaning devices that 
have a demonstrated and documented minimum removal efficiency of 99.97% 
of particles greater than or equal to 0.3 m in diameter. HEPA 
filters have been shown to be effective in reducing the concentration 
of Aspergillus spores (which range in size from 1.5 m to 6 
m) to below measurable levels (100-102). The ability of HEPA 
filters to remove tubercle bacilli from the air has not been studied, 
but M. tuberculosis droplet nuclei probably range from 1 m to 
5 m in diameter (i.e., approximately the same size as 
Aspergillus spores). Therefore, HEPA filters can be expected to remove 
infectious droplet nuclei from contaminated air. HEPA filters can be 
used to clean air before it is exhausted to the outside, recirculated 
to other areas of a facility, or recirculated within a room. If the 
device is not completely passive (e.g., it utilizes techniques such as 
electrostatics) and the failure of the electrostatic components permits 
loss of filtration efficiency to less than 99.97%, the device should 
not be used in systems that recirculate air back into the general 
facility ventilation system from TB isolation rooms and treatment rooms 
in which procedures are performed on patients who may have infectious 
TB (Suppl. 3, Section II.C.2).
    HEPA filters can be used in a number of ways to reduce or eliminate 
infectious droplet nuclei from room air or exhaust. These methods 
include placement of HEPA filters (a) in exhaust ducts to remove 
droplet nuclei from air being discharged to the outside, either 
directly or through ventilation equipment; (b) in ducts discharging 
room air into the general ventilation system; and (c) in fixed or 
portable room-air cleaners. The effectiveness of portable HEPA room-air 
cleaning units has not been evaluated adequately, and there is probably 
considerable variation in their effectiveness. HEPA filters can also be 
used in exhaust ducts or vents that discharge air from booths or 
enclosures into the surrounding room (Suppl. 3, Section II.A.3). In any 
application, HEPA filters should be installed carefully and maintained 
meticulously to ensure adequate function.
    Manufacturers of room-air cleaning equipment should provide 
documentation of the HEPA filter efficiency and the efficiency of the 
installed device in lowering room-air contaminant levels.
1. Use of HEPA Filtration When Exhausting Air to the Outside
    HEPA filters can be used as an added safety measure to clean air 
from isolation rooms and local exhaust devices (i.e., booths, tents, or 
hoods used for cough-inducing procedures) before exhausting it directly 
to the outside, but such use is unnecessary if the exhaust air cannot 
re-enter the ventilation system supply. The use of HEPA filters should 
be considered wherever exhaust air could possibly reenter the system.
    In many instances, exhaust air is not discharged directly to the 
outside; rather, the air is directed through heat-recovery devices 
(e.g., heat wheels). Heat wheels are often used to reduce the costs of 
operating ventilation systems (103). If such units are used with the 
system, a HEPA filter should also be used. As the wheel rotates, energy 
is transferred into or removed from the supply inlet air stream. The 
HEPA filter should be placed upstream from the heat wheel because of 
the potential for leakage across the seals separating the inlet and 
exhaust chambers and the theoretical possibility that droplet nuclei 
could be impacted on the wheel by the exhaust air and subsequently 
stripped off into the supply air.
2. Recirculation of HEPA-Filtered Air to Other Areas of a Facility
    Air from TB isolation rooms and treatment rooms used to treat 
patients who have confirmed or suspected infectious TB should be 
exhausted to the outside in accordance with applicable Federal, state, 
and local regulations. The air should not be recirculated into the 
general ventilation. In some instances, recirculation of air into the 
general ventilation system from such rooms is unavoidable (i.e., in 
existing facilities in which the ventilation system or facility 
configuration makes venting the exhaust to the outside impossible). In 
such cases, HEPA filters should be installed in the exhaust duct 
leading from the room to the general ventilation system to remove 
infectious organisms and particulates the size of droplet nuclei from 
the air before it is returned to the general ventilation system 
(Section II.F; Suppl. 3). Air from TB isolation rooms and treatment 
rooms in new or renovated facilities should not be recirculated into 
the general ventilation system.
3. Recirculation of HEPA-Filtered Air Within a Room
    Individual room-air recirculation can be used in areas where there 
is no general ventilation system, where an existing system is incapable 
of providing adequate airflow, or where an increase in ventilation is 
desired without affecting the fresh air supply or negative pressure 
system already in place. Recirculation of HEPA-filtered air within a 
room can be achieved in several ways: (a) by exhausting air from the 
room into a duct, filtering it through a HEPA filter installed in the 
duct, and returning it to the room (Figure S3-5); (b) by filtering air 
through HEPA recirculation systems mounted on the wall or ceiling of 
the room (Figure S3-6); or (c) by filtering air through portable HEPA 
recirculation systems. In this document, the first two of these 
approaches are referred to as fixed room-air recirculation systems, 
because the HEPA filter devices are fixed in place and are not easily 
movable.

BILLING CODE 4163-18-P

TN28OC94.008


BILLING CODE 4163-18-C
    a. Fixed room-air recirculation systems.
    The preferred method of recirculating HEPA-filtered air within a 
room is a built-in system, in which air is exhausted from the room into 
a duct, filtered through a HEPA filter, and returned to the room 
(Figure S3-5). This technique may be used to add air changes in areas 
where there is a recommended minimum ACH that is difficult to meet with 
general ventilation alone. The air does not have to be conditioned, 
other than by the filtration, and this permits higher airflow rates 
than the general ventilation system can usually achieve. An alternative 
is the use of HEPA filtration units that are mounted on the wall or 
ceiling of the room (Figure S3-7). Fixed recirculation systems are 
preferred over portable (free-standing) units because they can be 
installed and maintained with a greater degree of reliability.
    b. Portable room-air recirculation units.
    Portable HEPA filtration units may be considered for recirculating 
air within rooms in which there is no general ventilation system, where 
the system is incapable of providing adequate airflow, or where 
increased effectiveness in room airflow is desired. Effectiveness 
depends on circulating as much of the air in the room as possible 
through the HEPA filter, which may be difficult to achieve and 
evaluate. The effectiveness of a particular unit can vary depending on 
the room's configuration, the furniture and persons in the room, and 
placement of the HEPA filtration unit and the supply and exhaust 
grilles. Therefore, the effectiveness of the portable unit may vary 
considerably in rooms with different configurations or in the same room 
if moved from one location to another in the room. If portable units 
are used, caution should be exercised to ensure they can recirculate 
all or nearly all of the room air through the HEPA filter. Some 
commercially available units may not be able to meet this requirement 
because of design limitations or insufficient airflow capacity. In 
addition, units should be designed and operated to ensure that persons 
in the room cannot interfere with or otherwise compromise the 
functioning of the unit. Portable HEPA filtration units have not been 
evaluated adequately to determine their role in TB infection-control 
programs.
    Portable HEPA filtration units should be designed to achieve the 
equivalent of 12 ACH. They should also be designed to ensure 
adequate air mixing in all areas of the hospital rooms in which they 
are used, and they should not interfere with the current ventilation 
system.
    Some HEPA filtration units employ UVGI for disinfecting air after 
HEPA filtration. However, whether exposing the HEPA-filtered air to UV 
irradiation further decreases the concentration of contaminants is not 
known.
    c. Evaluation of room-air recirculation systems and units.
    Detailed and accurate evaluations of room-air recirculation systems 
and units require the use of sophisticated test equipment and lengthy 
test procedures that are not practical. However, an estimate of the 
unit's ability to circulate the air in the room can be made by 
visualizing airflow patterns as was described previously for estimating 
room air mixing (Suppl. 3, Section II.B.1). If the air movement is good 
in all areas of the room, the unit should be effective.
4. Installing, Maintaining, and Monitoring HEPA Filters
    Proper installation and testing and meticulous maintenance are 
critical if a HEPA filtration system is used (104), especially if the 
system used recirculates air to other parts of the facility. Improper 
design, installation, or maintenance could allow infectious particles 
to circumvent filtration and escape into the general ventilation system 
(47). HEPA filters should be installed to prevent leakage between 
filter segments and between the filter bed and its frame. A regularly 
scheduled maintenance program is required to monitor the HEPA filter 
for possible leakage and for filter loading. A quantitative leakage and 
filter performance test (e.g., the dioctal phthalate [DOP] penetration 
test [105]) should be performed at the initial installation and every 
time the filter is changed or moved. The test should be repeated every 
6 months for filters in general-use areas and in areas with systems 
that exhaust air that is likely to be contaminated with M. tuberculosis 
(e.g, TB isolation rooms).
    A manometer or other pressure-sensing device should be installed in 
the filter system to provide an accurate and objective means of 
determining the need for filter replacement. Pressure drop 
characteristics of the filter are supplied by the manufacturer of the 
filter. Installation of the filter should allow for maintenance that 
will not contaminate the delivery system or the area served. For 
general infection-control purposes, special care should be taken to not 
jar or drop the filter element during or after removal.
    The scheduled maintenance program should include procedures for 
installation, removal, and disposal of filter elements. HEPA filter 
maintenance should be performed only by adequately trained personnel. 
Appropriate respiratory protection should be worn while performing 
maintenance and testing procedures. In addition, filter housing and 
ducts leading to the housing should be labelled clearly with the words 
``Contaminated Air'' (or a similar warning).
    When a HEPA filter is used, one or more lower efficiency disposable 
prefilters installed upstream will extend the useful life of the HEPA 
filter. A disposable filter can increase the life of a HEPA filter by 
25%. If the disposable filter is followed by a 90% extended surface 
filter, the life of the HEPA filter can be extended almost 900% (98). 
These prefilters should be handled and disposed of in the same manner 
as the HEPA filter.
D. TB Isolation Rooms and Treatment Rooms
    Purpose: To separate patients who are likely to have infectious TB 
from other persons, to provide an environment that will allow reduction 
of the concentration of droplet nuclei through various engineering 
methods, and to prevent the escape of droplet nuclei from such rooms 
into the corridor and other areas of the facility using directional 
airflow.
    A hierarchy of ventilation methods used to achieve a reduction in 
the concentration of droplet nuclei and to achieve directional airflow 
using negative pressure has been developed (Table S3-2). The methods 
are listed in order from the most desirable to the least desirable. The 
method selected will depend on the configuration of the isolation room 
and the ventilation system in the facility; the determination should be 
made in consultation with a ventilation engineer.

   Table S3-2.--Hierarchy of Ventilation Methods for Tuberculosis (TB)  
                   Isolation Rooms and Treatment Rooms                  
------------------------------------------------------------------------
 Reducing concentration of airborne  Achieving directional airflow using
         tubercle bacilli*                negative pressure     
------------------------------------------------------------------------
1. Facility heating, ventilation,    1. Facility HVAC system.           
 and air-conditioning (HVAC) system.                                    
2. Fixed room-air high-efficiency    2. Bleed airSec.  from fixed room- 
 particulate air (HEPA)               air HEPA recirculation system.    
 recirculation system.                                                  
3. Wall- or ceiling-mounted room-    3. Bleed air from wall- or ceiling-
 air HEPA recirculation system.       mounted room-air HEPA             
                                      recirculation system.             
4. Portable room-air HEPA            4. Bleed air from portable room-air
 recirculation unit.                 HEPA recirculation unit.         
                                     5. Exhaust air from room through   
                                      window-mounted fan.**             
------------------------------------------------------------------------
*Ventilation methods are used to reduce the concentration of airborne   
  tubercle bacilli. If the facility HVAC system cannot achieve the      
  recommended ventilation rate, auxiliary room-air recirculation methods
  may be used. These methods are listed in order from the most desirable
  to the least desirable. Ultraviolet germicidal irradiation may be used
  as a supplement to any of the ventilation methods for air cleaning.   
Directional airflow using negative pressure can be achieved with
  the facility HVAC system and/or the auxiliary air-recirculation-      
  cleaning systems. These methods are listed in order from the most     
  desirable to the least desirable.                                     
Sec. To remove the amount of return air necessary to achieve negative   
  pressure.                                                             
The effectiveness of portable room-air HEPA recirculation units can    
  vary depending on the room's configuration, the furniture and persons 
  in the room, the placement of the unit, the supply and exhaust        
  grilles, and the achievable ventilation rates and air mixing. Units   
  should be designed and operated to ensure that persons in the room    
  cannot interfere with or otherwise compromise the function of the     
  unit. Fixed recirculating systems are preferred over portable units in
  TB isolation rooms of facilities in which services are provided       
  regularly to TB patients.                                             
**This method simply achieves negative pressure and should be used only 
  as a temporary measure.                                               

1. Preventing the Escape of Droplet Nuclei From the Room
    Rooms used for TB isolation should be single-patient rooms with 
negative pressure relative to the corridor or other areas connected to 
the room. Doors between the isolation room and other areas should 
remain closed except for entry into or exit from the room. The room's 
openings (e.g., windows and electrical and plumbing entries) should be 
sealed as much as possible. However, a small gap of \1/8\ to \1/2\ inch 
should be at the bottom of the door to provide a controlled airflow 
path. Proper use of negative pressure will prevent contaminated air 
from escaping the room.
2. Reducing the Concentration of Droplet Nuclei in the Room
    ASHRAE (47), AIA (48), and the Health Resources and Services 
Administration (49) recommend a minimum of 6 ACH for TB isolation rooms 
and treatment rooms. This ventilation rate is based on comfort- and 
odor-control considerations. The effectiveness of this level of airflow 
in reducing the concentration of droplet nuclei in the room, thus 
reducing the transmission of airborne pathogens, has not been evaluated 
directly or adequately.
    Ventilation rates >6 ACH are likely to produce an incrementally 
greater reduction in the concentration of bacteria in a room than are 
lower rates (50-52). However, accurate quantitation of decreases in 
risk that would result from specific increases in general ventilation 
levels has not been performed and may not be possible.
    To reduce the concentration of droplet nuclei, TB isolation rooms 
and treatment rooms in existing health-care facilities should have an 
airflow of 6 ACH. Where feasible, this airflow rate should 
be increased to 12 ACH by adjusting or modifying the 
ventilation system or by using auxiliary means (e.g., recirculation of 
air through fixed HEPA filtration units or portable air cleaners) 
(Suppl. 3, Section II.C) (53). New construction or renovation of 
existing health-care facilities should be designed so that TB isolation 
rooms achieve an airflow of 12 ACH.
3. Exhaust From TB Isolation Rooms and Treatment Rooms
    Air from TB isolation rooms and treatment rooms in which patients 
with infectious TB may be examined should be exhausted directly to the 
outside of the building and away from air-intake vents, persons, and 
animals in accordance with federal, state, and local regulations 
concerning environmental discharges. (See Suppl. 3, Section II.C, for 
information regarding recirculation of exhaust air.) Exhaust ducts 
should not be located near areas that may be populated (e.g., near 
sidewalks or windows that could be opened). Ventilation system exhaust 
discharges and inlets should be designed to prevent reentry of 
exhausted air. Wind blowing over a building creates a highly turbulent 
recirculation zone, which can cause exhausted air to reenter the 
building (Figure S3-7). Exhaust flow should be discharged above this 
zone (Suppl. 3, Section II.C.1). Design guidelines for proper placement 
of exhaust ducts can be found in the 1989 ASHRAE Fundamentals Handbook 
(106). If recirculation of air from such rooms into the general 
ventilation system is unavoidable, the air should be passed through a 
HEPA filter before recirculation (Suppl. 3, Section II.C.2).

TN28OC94.009

4. Alternatives to TB Isolation Rooms
    Isolation can also be achieved by use of negative-pressure 
enclosures (e.g, tents or booths) (Suppl. 3, Section II.A.1). These can 
be used to provide patient isolation in areas such as emergency rooms 
and medical testing and treatment areas and to supplement isolation in 
designated isolation rooms.

III. UVGI

    Purpose: To kill or inactivate airborne tubercle bacilli.
    Research has demonstrated that UVGI is effective in killing or 
inactivating tubercle bacilli under experimental conditions (66,107-
110) and in reducing transmission of other infections in hospitals 
(111), military housing (112), and classrooms (113-115). Because of the 
results of numerous studies (116-120) and the experiences of TB 
clinicians and mycobacteriologists during the past several decades, the 
use of UVGI has been recommended as a supplement to other TB infection-
control measures in settings where the need for killing or inactivating 
tubercle bacilli is important (2,4,121-125).
    UV radiation is defined as that portion of the electromagnetic 
spectrum described by wavelengths from 100 to 400 nm. For convenience 
of classification, the UV spectrum has been separated into three 
different wavelength bands: UV-A (long wavelengths, range: 320-400 nm), 
UV-B (midrange wavelengths, range: 290-320 nm), and UV-C (short 
wavelengths, range: 100-290 nm) (126). Commercially available UV lamps 
used for germicidal purposes are low-pressure mercury vapor lamps (127) 
that emit radiant energy in the UV-C range, predominantly at a 
wavelength of 253.7 nm (128).
A. Applications
    UVGI can be used as a method of air disinfection to supplement 
other engineering controls. Two systems of UVGI can be used for this 
purpose: duct irradiation and upper-room air irradiation.
1. Duct Irradiation
    Purpose: To inactivate tubercle bacilli without exposing persons to 
UVGI.
    In duct irradiation systems, UV lamps are placed inside ducts that 
remove air from rooms to disinfect the air before it is recirculated. 
When UVGI duct systems are properly designed, installed, and 
maintained, high levels of UV radiation may be produced in the duct 
work. The only potential for human exposure to this radiation occurs 
during maintenance operations.
    Duct irradiation may be used:
     In a TB isolation room or treatment room to recirculate 
air from the room, through a duct containing UV lamps, and back into 
the room. This recirculation method can increase the overall room 
airflow but does not increase the supply of fresh outside air to the 
room.
     In other patients' rooms and in waiting rooms, emergency 
rooms, and other general-use areas of a facility where patients with 
undiagnosed TB could potentially contaminate the air, to recirculate 
air back into the general ventilation. Duct-irradiation systems are 
dependent on airflow patterns within a room that ensure that all or 
nearly all of the room air circulates through the duct.
2. Upper-Room Air Irradiation
    Purpose: To inactivate tubercle bacilli in the upper part of the 
room, while minimizing radiation exposure to persons in the lower part 
of the room.
    In upper-room air irradiation, UVGI lamps are suspended from the 
ceiling or mounted on the wall. The bottom of the lamp is shielded to 
direct the radiation upward but not downward. The system depends on air 
mixing to take irradiated air from the upper to the lower part of the 
room, and nonirradiated air from the lower to the upper part. The 
irradiated air space is much larger than that in a duct system.
    UVGI has been effective in killing bacteria under conditions where 
air mixing was accomplished mainly by convection. For example, BCG was 
atomized in a room that did not have supplemental ventilation (120), 
and in another study a surrogate bacteria, Serratia marcesens, was 
aerosolized in a room with a ventilation rate of 6 ACH (129). These 
reports estimated the effect of UVGI to be equivalent to 10 and 39 ACH, 
respectively, for the organisms tested, which are less resistant to 
UVGI than M. tuberculosis (120). The addition of fans or some heating/
air conditioning arrangements may double the effectiveness of UVGI 
lamps (130-132). Greater rates of ventilation, however, may decrease 
the length of time the air is irradiated, thus decreasing the killing 
of bacteria (117,129). The optimal relationship between ventilation and 
UVGI is not known. Air irradiation lamps used in corridors have been 
effective in killing atomized S. marcesens (133). Use of UVGI lamps in 
an outpatient room has reduced culturable airborne bacteria by 14%-19%. 
However, the irradiation did not reduce the concentration of gram-
positive, rod-shaped bacteria; although fast-growing mycobacteria were 
cultured, M. tuberculosis could not be recovered from the room's air 
samples because of fungal overgrowth of media plates (134).
    Upper-room air UVGI irradiation may be used:
     In isolation or treatment rooms as a supplemental method 
of air cleaning.
     In other patients' rooms and in waiting rooms, emergency 
rooms, corridors, and other central areas of a facility where patients 
with undiagnosed TB could potentially contaminate the air. Determinants 
of UVGI effectiveness include room configuration, UV lamp placement, 
and the adequacy of airflow patterns in bringing contaminated air into 
contact with the irradiated upper-room space. Air mixing may be 
facilitated by supplying cool air near the ceiling in rooms where 
warmer air (or a heating device) is present below. The ceiling should 
be high enough for a large volume of upper-room air to be irradiated 
without HCWs and patients being overexposed to UV radiation.
B. Limitations
    Because the clinical effectiveness of UV systems varies, and 
because of the risk for transmission of M. tuberculosis if a system 
malfunctions or is maintained improperly, UVGI is not recommended for 
the following specific applications:
    1. Duct systems using UVGI are not recommended as a substitute for 
HEPA filters if air from isolation rooms must be recirculated to other 
areas of a facility.
    2. UVGI alone is not recommended as a substitute for HEPA 
filtration or local exhaust of air to the outside from booths, tents, 
or hoods used for cough-inducing procedures.
    3. UVGI is not a substitute for negative pressure.
    The use of UV lamps and HEPA filtration in a single unit would not 
be expected to have any infection-control benefits not provided by use 
of the HEPA filter alone.
    The effectiveness of UVGI in killing airborne tubercle bacilli 
depends on the intensity of UVGI, the duration of contact the organism 
has with the irradiation, and the relative humidity (66,108,111). 
Humidity can have an adverse effect on UVGI effectiveness at levels 
>70% relative humidity for S. marcescens (135). The interaction of 
these factors has not been fully defined, however, making precise 
recommendations for individual UVGI installations difficult to develop.
    Old lamps or dust-covered UV lamps are less effective; therefore, 
regular maintenance of UVGI systems is crucial.
C. Safety Issues
    Short-term overexposure to UV radiation can cause erythema and 
keratoconjunctivitis (136,137). Broad-spectrum UV radiation has been 
associated with increased risk for squamous and basal cell carcinomas 
of the skin (138). UV-C was recently classified by the International 
Agency for Research on Cancer as ``probably carcinogenic to humans 
(Group 2A)'' (138). This classification is based on studies suggesting 
that UV-C radiation can induce skin cancers in animals; DNA damage, 
chromosomal aberrations and sister chromatid exchange and 
transformation in human cells in vitro; and DNA damage in mammalian 
skin cells in vivo. In the animal studies, a contribution of UV-B to 
the tumor effects could not be excluded, but the effects were greater 
than expected for UV-B alone (138). Although some recent studies have 
demonstrated that UV radiation can activate HIV gene promoters (i.e., 
the genes in HIV that prompt replication of the virus) in laboratory 
samples of human cells (139-144), the implications of these in vitro 
findings for humans are unknown.
    In 1972, the National Institute for Occupational Safety and Health 
(NIOSH) published a recommended exposure limit (REL) for occupational 
exposure to UV radiation (136). The REL is intended to protect workers 
from the acute effects of UV exposure (e.g., erythema and 
photokeratoconjunctivitis). However, photosensitive persons and those 
exposed concomitantly to photoactive chemicals may not be protected by 
the recommended standard. If proper procedures are not followed, HCWs 
performing maintenance on such fixtures are at risk for exposure to UV 
radiation. Because UV fixtures used for upper-room air irradiation are 
present in rooms, rather than hidden in ducts, safety may be much more 
difficult to achieve and maintain. Fixtures must be designed and 
installed to ensure that UV exposure to persons in the room (including 
HCWs and inpatients) are below current safe exposure levels. Recent 
health hazard evaluations conducted by CDC have noted problems with 
overexposure of HCWs to UVGI and with inadequate maintenance, training, 
labelling, and use of personal protective equipment (145-147).
    The current number of persons who are properly trained in UVGI 
system design and installation is limited. CDC strongly recommends that 
a competent UVGI system designer be consulted to address safety 
considerations before such a system is procured and installed. Experts 
who might be consulted include industrial hygienists, engineers, and 
health physicists. Principles for the safe installation of UV lamp 
fixtures have been developed and can be used as guidelines (148,149).
    If UV lamps are being used in a facility, the general TB education 
of HCWs should include:
    1. The basic principles of UVGI systems (i.e., how they work and 
what their limitations are).
    2. The potential hazardous effects of UVGI if overexposure occurs.
    3. The potential for photosensitivity associated with certain 
medical conditions or use of some medications.
    4. The importance of general maintenance procedures for UVGI 
fixtures.
    Exposure to UV intensities above the REL should be avoided. 
Lightweight clothing made of tightly woven fabric and UV-absorbing 
sunscreens with solar-protection factors (SPFs) 15 may help 
protect photosensitive persons. HCWs should be advised that any eye or 
skin irritation that develops after UV exposure should be examined by 
occupational health staff.
D. Exposure Criteria for UV Radiation
    The NIOSH REL for UV radiation is wavelength dependent because 
different wavelengths of UV radiation have different adverse effects on 
the skin and eyes (136). Relative spectral effectiveness (S) 
is used to compare various UV sources with a source producing UV 
radiation at 270 nm, the wavelength of maximum ocular sensitivity. For 
example, the S at 254 nm is 0.5; therefore, twice as much 
energy is required at 254 nm to produce an identical biologic effect at 
270 nm (136). Thus, at 254 nm, the NIOSH REL is 0.006 joules per square 
centimeter (J/cm\2\); and at 270 nm, it is 0.003 J/cm\2\.
    For germicidal lamps that emit radiant energy predominantly at a 
wavelength of 254 nm, proper use of the REL requires that the measured 
irradiance level (E) in microwatts per square centimeter (W/
cm2) be multiplied by the relative spectral effectiveness at 254 
nm (0.5) to obtain the effective irradiance (Eeff). The maximum 
permissible exposure time can then be determined for selected values of 
Eeff (Table S3-3), or it can be calculated (in seconds) by 
dividing 0.003 J/cm2 (the NIOSH REL at 270 nm) by Eeff in 
W/cm2 (136,150).
    To protect HCWs who are exposed to germicidal UV radiation for 8 
hours per workday, the measured irradiance (E) should be 0.2 
W/cm2. This is calculated by obtaining Eeff (0.1 
W/cm2) (Table S3-3) and then dividing this value by 
S (0.5). 

 Table S3-3.--Maximum Permissible Exposure Times* for Selected Values of
                          Effective Irradiance                          
------------------------------------------------------------------------
                                                             Effective  
                                                            irradiance  
           Permissible exposure time per day              (Eeff)
                                                           (W/ 
                                                               cm2)     
------------------------------------------------------------------------
8 hrs...................................................            0.1 
4 hrs...................................................            0.2 
2 hrs...................................................            0.4 
1 hr....................................................            0.8 
30 min..................................................            1.7 
15 min..................................................            3.3 
10 min..................................................            5.0 
5 min...................................................           10.0 
1 min...................................................           50.0 
30 sec..................................................         100.0  
------------------------------------------------------------------------
*Permissible exposure times are designed to prevent acute effects of    
  irradiation to skin and eyes (136). These recommended limits are      
  wavelength dependent because different wavelengths of ultraviolet (UV)
  radiation have different adverse effects on these organs.             
Relative spectral effectiveness (S) is used to compare 
  various UV sources with a source producing UV radiation at 270 nm, the
  wavelength of maximum ocular sensitivity. For example, the relative   
  spectral effectiveness at 254 nm is 0.5; therefore, twice as much     
  energy is required at 254 nm to produce an identical biologic effect  
  at 270 nm. At 254 nm, the NIOSH REL is 0.006 joules per square        
  centimeter (J/cm2); and at 270 nm, it is 0.003 J/cm2. For germicidal  
  lamps that emit radiant energy predominantly at a wavelength of 254   
  nm, proper use of the REL requires that the measured irradiance level 
  (E) in microwatts per square centimeter (W/cm2) be multiplied
  by the relative spectral effectiveness at 254 nm (0.5) to obtain Eeff.
  The maximum permissible exposure time can be calculated (in seconds)  
  by dividing 0.003 J/cm2 (the NIOSH REL at 270 nm) by Eeff in W/cm2 (136,150). To protect health-care workers who are exposed to  
  germicidal UV radiation for 8 hours per work day, the measured        
  irradiance (E) should be 0.2 W/cm2, which is      
  calculated by obtaining Eeff (0.1 W/cm2), then dividing this 
  value by S (0.5).                                            

E. Maintenance and Monitoring
1. Labelling and Posting
    Warning signs should be posted on UV lamps and wherever high-
intensity (i.e., UV exposure greater than the REL) germicidal UV 
irradiation is present (e.g., upper-room air space and accesses to 
ducts [if duct irradiation is used]) to alert maintenance staff or 
other HCWs of the hazard. Some examples are shown below:
CAUTION
ULTRAVIOLET ENERGY: TURN OFF LAMPS BEFORE ENTERING UPPER ROOM
CAUTION
ULTRAVIOLET ENERGY: PROTECT EYES & SKIN
2. Maintenance
    Because the intensity of UV lamps fluctuates as they age, a 
schedule for replacing the lamps should be developed. The schedule can 
be determined from either a time/use log or a system based on 
cumulative time. The tube should be checked periodically for dust 
build-up, which lessens the output of UVGI. If the tube is dirty, it 
should be allowed to cool, then cleaned with a damp cloth. Tubes should 
be replaced if they stop glowing or if they flicker to an objectionable 
extent. Maintenance personnel must turn off all UV tubes before 
entering the upper part of the room or before accessing ducts for any 
purpose. Only a few seconds of direct exposure to the intense UV 
radiation in the upper-room air space or in ducts can cause burns. 
Protective equipment (e.g., gloves and goggles [and/or face shields]) 
should be worn if exposure greater than the recommended standard is 
anticipated.
    Banks of UVGI tubes can be installed in ventilating ducts. Safety 
devices should be used on access doors to eliminate hazard to 
maintenance personnel. For duct irradiation systems, the access door 
for servicing the lamps should have an inspection window* through which 
the lamps are checked periodically for dust build-up and 
malfunctioning. The access door should have a warning sign written in 
languages appropriate for maintenance personnel to alert them to the 
health hazard of looking directly at bare tubes. The lock for this door 
should have an automatic electric switch or other device that turns off 
the lamps when the door is opened.
---------------------------------------------------------------------------

    *Ordinary glass (not quartz) is sufficient to filter out UV 
radiation.
---------------------------------------------------------------------------

    Two types of fixtures are used in upper-room air irradiation: wall-
mounted fixtures that have louvers to block downward radiation and 
ceiling-mounted fixtures that have baffles to block radiation below the 
horizontal plane of the UV tube. The actual UV tube in either type of 
fixture must not be visible from any normal position in the room. Light 
switches that can be locked should be used, if possible, to prevent 
injury to personnel who might unintentionally turn the lamps on during 
maintenance procedures. In most applications, properly shielding the UV 
lamps to provide protection from most, if not all, of the direct UV 
radiation is not difficult. However, radiation reflected from glass, 
polished metal, and high-gloss ceramic paints can be harmful to persons 
in the room, particularly if more than one UV lamp is in use. Surfaces 
in irradiated rooms that can reflect UVGI into occupied areas of the 
room should be covered with non-UV reflecting material.
3. Monitoring
    A regularly scheduled evaluation of the UV intensity to which HCWs, 
patients, and others are exposed should be conducted.
    UV measurements should be made in various locations within a room 
using a detector designed to be most sensitive at 254 nm. Equipment 
used to measure germicidal UV radiation should be maintained and 
calibrated on a regular schedule.
    A new UV installation must be carefully checked for hot spots 
(i.e., areas of the room where the REL is exceeded) by an industrial 
hygienist or other person knowledgeable in making UV measurements. UV 
radiation levels should not exceed those in the recommended guidelines.

Supplement 4: Respiratory Protection

I. Considerations for Selection of Respirators
    Personal respiratory protection should be used by (a) persons 
entering rooms where patients with known or suspected infectious TB are 
being isolated, (b) persons present during cough-inducing or aerosol-
generating procedures performed on such patients, and (c) persons in 
other settings where administrative and engineering controls are not 
likely to protect them from inhaling infectious airborne droplet 
nuclei. These other settings should be identified on the basis of the 
facility's risk assessment.
    Although data regarding the effectiveness of respiratory protection 
from many hazardous airborne materials have been collected, the precise 
level of effectiveness in protecting HCWs from M. tuberculosis 
transmission in health-care settings has not been determined. 
Information concerning the transmission of M. tuberculosis is 
incomplete. Neither the smallest infectious dose of M. tuberculosis nor 
the highest level of exposure to M. tuberculosis at which transmission 
will not occur has been defined conclusively (59,151,152). Furthermore, 
the size distribution of droplet nuclei and the number of particles 
containing viable M. tuberculosis that are expelled by infectious TB 
patients have not been defined adequately, and accurate methods of 
measuring the concentration of infectious droplet nuclei in a room have 
not been developed.
    Nevertheless, in certain settings the administrative and 
engineering controls may not adequately protect HCWs from airborne 
droplet nuclei (e.g., in TB isolation rooms, treatment rooms in which 
cough-inducing or aerosol-generating procedures are performed, and 
ambulances during the transport of infectious TB patients). Respiratory 
protective devices used in these settings should have characteristics 
that are suitable for the organism they are protecting against and the 
settings in which they are used.
A. Performance Criteria for Personal Respirators for Protection Against 
Transmission of M. tuberculosis
    Respiratory protective devices used in health-care settings for 
protection against M. tuberculosis should meet the following standard 
criteria. These criteria are based on currently available information, 
including (a) data on the effectiveness of respiratory protection 
against noninfectious hazardous materials in workplaces other than 
health-care settings and on an interpretation of how these data can be 
applied to respiratory protection against M. tuberculosis; (b) data on 
the efficiency of respirator filters in filtering biological aerosols; 
(c) data on face-seal leakage; and (d) data on the characteristics of 
respirators that were used in conjunction with administrative and 
engineering controls in outbreak settings where transmission to HCWs 
and patients was terminated.
    1. The ability to filter particles 1 um in size in the unloaded 
state with a filter efficiency of 95% (i.e., filter leakage 
of 5%), given flow rates of up to 50 L per minute.
    Available data suggest that infectious droplet nuclei range in size 
from 1 m to 5 m; therefore, respirators used in 
health-care settings should be able to efficiently filter the smallest 
particles in this range. Fifty liters per minute is a reasonable 
estimate of the highest airflow rate an HCW is likely to achieve during 
breathing, even while performing strenuous work activities.
    2. The ability to be qualitatively or quantitatively fit tested in 
a reliable way to obtain a face-seal leakage of 10% (54,55).
    3. The ability to fit the different facial sizes and 
characteristics of HCWs, which can usually be met by making the 
respirators available in at least three sizes.
    4. The ability to be checked for facepiece fit, in accordance with 
OSHA standards and good industrial hygiene practice, by HCWs each time 
they put on their respirators (54,55).
    In some settings, HCWs may be at risk for two types of exposure: 
(a) inhalation of M. tuberculosis and (b) mucous membrane exposure to 
fluids that may contain bloodborne pathogens. In these settings, 
protection against both types of exposure should be used.
    When operative procedures (or other procedures requiring a sterile 
field) are performed on patients who may have infectious TB, 
respiratory protection worn by the HCW should serve two functions: (a) 
it should protect the surgical field from the respiratory secretions of 
the HCW and (b) it should protect the HCW from infectious droplet 
nuclei that may be expelled by the patient or generated by the 
procedure. Respirators with expiration valves and positive-pressure 
respirators do not protect the sterile field; therefore, a respirator 
that does not have a valve and that meets the criteria in Supplement 4, 
Section I.A, should be used.
B. Specific Respirators
    The OSHA respiratory protection standard requires that all 
respiratory protective devices used in the workplace be certified by 
NIOSH.* NIOSH-approved HEPA respirators are the only currently 
available air-purifying respirators that meet or exceed the standard 
performance criteria stated above. However, the NIOSH certification 
procedures are currently being revised (153). Under the proposed 
revision, filter materials would be tested at a flow rate of 85 L/min 
for penetration by particles with a median aerodynamic diameter of 0.3 
m and, if certified, would be placed in one of the following 
categories: type A, which has 99.97% efficiency (similar to 
current HEPA filter media); type B, 99% efficiency; or type 
C, 95% efficiency. According to this proposed scheme, type C 
filter material would meet or exceed the standard performance criteria 
specified in this document.
---------------------------------------------------------------------------

    *29 CFR 1910.134.
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    The facility's risk assessment may identify a limited number of 
selected settings (e.g., bronchoscopy performed on patients suspected 
of having TB or autopsy performed on deceased persons suspected of 
having had active TB at the time of death) where the estimated risk for 
transmission of M. tuberculosis may be such that a level of respiratory 
protection exceeding the standard criteria is appropriate. In such 
circumstances, a level of respiratory protection exceeding the standard 
criteria and compatible with patient-care delivery (e.g., negative-
pressure respirators that are more protective; powered air-purifying 
particulate respirators [PAPRs]; or positive-pressure airline, half-
mask respirators) should be provided by employers to HCWs who are 
exposed to M. tuberculosis. Information on these and other respirators 
may be found in the NIOSH Guide to Industrial Respiratory Protection 
(55).
C. The Effectiveness of Respiratory Protective Devices
    The following information, which is based on experience with 
respiratory protection in the industrial setting, summarizes the 
available data about the effectiveness of respiratory protection 
against hazardous airborne materials. Data regarding protection against 
transmission of M. tuberculosis are not available.
    The parameters used to determine the effectiveness of a respiratory 
protective device are face-seal efficacy and filter efficacy.
1. Face-Seal Leakage
    Face-seal leakage compromises the ability of particulate 
respirators to protect HCWs from airborne materials (154-156). A proper 
seal between the respirator's sealing surface and the face of the 
person wearing the respirator is essential for effective and reliable 
performance of any negative-pressure respirator. This seal is less 
critical, but still important, for positive-pressure respirators. Face-
seal leakage can result from various factors, including incorrect 
facepiece size or shape, incorrect or defective facepiece sealing-lip, 
beard growth, perspiration or facial oils that can cause facepiece 
slippage, failure to use all the head straps, incorrect positioning of 
the facepiece on the face, incorrect head strap tension or position, 
improper respirator maintenance, and respirator damage.
    Every time a person wearing a negative-pressure particulate 
respirator inhales, a negative pressure (relative to the workplace air) 
is created inside the facepiece. Because of this negative pressure, air 
containing contaminants can take a path of least resistance into the 
respirator--through leaks at the face-seal interface--thus avoiding the 
higher-resistance filter material. Currently available, cup-shaped, 
disposable particulate respirators have from 0 to 20% face-seal leakage 
(55,154). This face-seal leakage results from the variability of the 
human face and from limitations in the respirator's design, 
construction, and number of sizes available. The face-seal leakage is 
probably higher if the respirator is not fitted properly to the HCW's 
face, tested for an adequate fit by a qualified person, and then 
checked for fit by the HCW every time the respirator is put on. Face-
seal leakage may be reduced to less than <10% with improvements in 
design, a greater variety in available sizes, and appropriate fit 
testing and fit checking.
    In comparison with negative-pressure respirators, positive-pressure 
respirators produce a positive pressure inside the facepiece under most 
conditions of use. For example, in a PAPR, a blower forcibly draws 
ambient air through HEPA filters, then delivers the filtered air to the 
facepiece. This air is blown into the facepiece at flow rates that 
generally exceed the expected inhalation flow rates. The positive 
pressure inside the facepiece reduces face-seal leakage to low levels, 
particularly during the relatively low inhalation rates expected in 
health-care settings. PAPRs with a tight-fitting facepiece have <2% 
face-seal leakage under routine conditions (55). Powered-air 
respirators with loose-fitting facepieces, hoods, or helmets have <4% 
face-seal leakage under routine conditions (55). Thus, a PAPR may offer 
lower levels of face-seal leakage than nonpowered, half-mask 
respirators. Full facepiece, nonpowered respirators have the same 
leakage (i.e., <2%) as PAPRs.
    Another factor contributing to face-seal leakage of cup-shaped, 
disposable respirators is that some of these respirators are available 
in only one size. A single size may produce higher leakage for persons 
who have smaller or difficult-to-fit faces (157). The facepieces used 
for some reusable (including HEPA and replaceable filter, negative-
pressure) and all positive-pressure particulate air-purifying 
respirators are available in as many as three different sizes.
2. Filter Leakage
    Aerosol leakage through respirator filters depends on at least five 
independent variables: (a) the filtration characteristics for each type 
of filter, (b) the size distribution of the droplets in the aerosol, 
(c) the linear velocity through the filtering material, (d) the filter 
loading (i.e., the amount of contaminant deposited on the filter), and 
(e) any electrostatic charges on the filter and on the droplets in the 
aerosol (158).
    When HEPA filters are used in particulate air-purifying 
respirators, filter efficiency is so high (i.e., effectively 100%) that 
filter leakage is not a consideration. Therefore, for all HEPA-filter 
respirators, virtually all inward leakage of droplet nuclei occurs at 
the respirator's face seal.
3. Fit Testing
    Fit testing is part of the respiratory protection program required 
by OSHA for all respiratory protective devices used in the workplace. A 
fit test determines whether a respiratory protective device adequately 
fits a particular HCW. The HCW may need to be fit tested with several 
devices to determine which device offers the best fit. However, fit 
tests can detect only the leakage that occurs at the time of the fit 
testing, and the tests cannot distinguish face-seal leakage from filter 
leakage.
    Determination of facepiece fit can involve qualitative or 
quantitative tests (55). A qualitative test relies on the subjective 
response of the HCW being fit tested. A quantitative test uses 
detectors to measure inward leakage.
    Disposable, negative-pressure particulate respirators can be 
qualitatively fit tested with aerosolized substances that can be 
tasted, although the results of this testing are limited because the 
tests depend on the subjective response of the HCW being tested. 
Quantitative fit testing of disposable negative-pressure particulate 
respirators can best be performed if the manufacturer provides a test 
respirator with a probe for this purpose.
    Replaceable filter, negative-pressure particulate respirators and 
all positive-pressure particulate respirators can be fit tested 
reliably, both qualitatively and quantitatively, when fitted with HEPA 
filters.
4. Fit Checking
    A fit check is a maneuver that an HCW performs before each use of 
the respiratory protective device to check the fit. The fit check can 
be performed according to the manufacturer's facepiece fitting 
instructions by using the applicable negative-pressure or positive-
pressure test.
    Some currently available cup-shaped, disposable negative-pressure 
particulate respirators cannot be fit checked reliably by persons 
wearing the devices because occluding the entire surface of the filter 
is difficult. Strategies for overcoming these limitations are being 
developed by respirator manufacturers.
5. Reuse of Respirators
    Conscientious respirator maintenance should be an integral part of 
an overall respirator program. This maintenance applies both to 
respirators with replaceable filters and respirators that are 
classified as disposable but that are reused. Manufacturers' 
instructions for inspecting, cleaning, and maintaining respirators 
should be followed to ensure that the respirator continues to function 
properly (55).
    When respirators are used for protection against noninfectious 
aerosols (e.g., wood dust), which may be present in the air in heavy 
concentrations, the filter material may become occluded with airborne 
material. This occlusion may result in an uncomfortable breathing 
resistance. In health-care settings where respirators are used for 
protection against biological aerosols, the concentration of infectious 
particles in the air is probably low; thus, the filter material in a 
respirator is very unlikely to become occluded with airborne material. 
In addition, there is no evidence that particles impacting on the 
filter material in a respirator are re-aerosolized easily. For these 
reasons, the filter material used in respirators in the health-care 
setting should remain functional for weeks to months. Respirators with 
replaceable filters are reusable, and a respirator classified as 
disposable may be reused by the same HCW as long as it remains 
functional.
    Before each use, the outside of the filter material should be 
inspected. If the filter material is physically damaged or soiled, the 
filter should be changed (in the case of respirators with replaceable 
filters) or the respirator discarded (in the case of disposable 
respirators). Infection-control personnel should develop standard 
operating procedures for storing, reusing, and disposing of respirators 
that have been designated as disposable and for disposing of 
replaceable filter elements.

II. Implementing a Personal Respiratory Protection Program

    If personal respiratory protection is used in a health-care 
setting, OSHA requires that an effective personal respiratory 
protection program be developed, implemented, administered, and 
periodically reevaluated (54,55).
    All HCWs who need to use respirators for protection against 
infection with M. tuberculosis should be included in the respiratory 
protection program. Visitors to TB patients should be given respirators 
to wear while in isolation rooms, and they should be given general 
instructions on how to use their respirators.
    The number of HCWs included in the respiratory protection program 
in each facility will vary depending on (a) the number of potentially 
infectious TB patients, (b) the number of rooms or areas to which 
patients with suspected or confirmed infectious TB are admitted, and 
(c) the number of HCWs needed in these rooms or areas. Where 
respiratory protection programs are required, they should include 
enough HCWs to provide adequate care for a patient with known or 
suspected TB should such a patient be admitted to the facility. 
However, administrative measures should be used to limit the number of 
HCWs who need to enter these rooms or areas, thus limiting the number 
of HCWs who need to be included in the respiratory protection program.
    Information regarding the development and management of a 
respiratory protection program is available in technical training 
courses that cover the basics of personal respiratory protection. Such 
courses are offered by various organizations, such as NIOSH, OSHA, and 
the American Industrial Hygiene Association. Similar courses are 
available from private contractors and universities.
    To be effective and reliable, respiratory protection programs must 
contain at least the following elements (55,154):
    1. Assignment of responsibility. Supervisory responsibility for the 
respiratory protection program should be assigned to designated persons 
who have expertise in issues relevant to the program, including 
infectious diseases and occupational health.
    2. Standard operating procedures. Written standard operating 
procedures should contain information concerning all aspects of the 
respiratory protection program.
    3. Medical screening. HCWs should not be assigned a task requiring 
use of respirators unless they are physically able to perform the task 
while wearing the respirator. HCWs should be screened for pertinent 
medical conditions at the time they are hired, then rescreened 
periodically (55). The screening could occur as infrequently as every 5 
years. The screening process should begin with a general screening 
(e.g., a questionnaire) for pertinent medical conditions, and the 
results of the screening should then be used to identify HCWs who need 
further evaluation. Routine physical examination or testing with chest 
radiographs or spirometry is not necessary or required.
    Few medical conditions preclude the use of most negative-pressure 
particulate respirators. HCWs who have mild pulmonary or cardiac 
conditions may report discomfort with breathing when wearing negative-
pressure particulate respirators, but these respirators are unlikely to 
have adverse health effects on the HCWs. Those HCWs who have more 
severe cardiac or pulmonary conditions may have more difficulty than 
HCWs with similar but milder conditions if performing duties while 
wearing negative-pressure respirators. Furthermore, these HCWs may be 
unable to use some PAPRs because of the added weight of these 
respirators.
    4. Training. HCWs who wear respirators and the persons who 
supervise them should be informed about the necessity for wearing 
respirators and the potential risks associated with not doing so. This 
training should also include at a minimum:
     The nature, extent, and specific hazards of M. 
tuberculosis transmission in their respective health-care facility.
     A description of specific risks for TB infection among 
persons exposed to M. tuberculosis, of any subsequent treatment with 
INH or other chemoprophylactic agents, and of the possibility of active 
TB disease.
     A description of engineering controls and work practices 
and the reasons why they do not eliminate the need for personal 
respiratory protection.
     An explanation for selecting a particular type of 
respirator, how the respirator is properly maintained and stored, and 
the operation, capabilities, and limitations of the respirator 
provided.
     Instruction in how the HCW wearing the respirator should 
inspect, put on, fit check, and correctly wear the provided respirator 
(i.e., achieve and maintain proper face-seal fit on the HCW's face).
     An opportunity to handle the provided respirator and learn 
how to put it on, wear it properly, and check the important parts.
     Instruction in how to recognize an inadequately 
functioning respirator.
    5. Face-seal fit testing and fit checking. HCWs should undergo fit 
testing to identify a respirator that adequately fits each individual 
HCW. The HCW should receive fitting instructions that include 
demonstrations and practice in how the respirator should be worn, how 
it should be adjusted, and how to determine if it fits properly. The 
HCW should be taught to check the facepiece fit before each use.
    6. Respirator inspection, cleaning, maintenance, and storage. 
Conscientious respirator maintenance should be an integral part of an 
overall respirator program. This maintenance applies both to 
respirators with replaceable filters and respirators that are 
classified as disposable but that are reused. Manufacturers' 
instructions for inspecting, cleaning, and maintaining respirators 
should be followed to ensure that the respirator continues to function 
properly (55).
    7. Periodic evaluation of the personal respiratory protection 
program. The program should be evaluated completely at least once a 
year, and both the written operating procedures and program 
administration should be revised as necessary based on the results of 
the evaluation. Elements of the program that should be evaluated 
include work practices and employee acceptance of respirator use (i.e., 
subjective comments made by employees concerning comfort during use and 
interference with duties).

Supplement 5: Decontamination--Cleaning, Disinfecting, and Sterilizing 
of Patient-Care Equipment

    Equipment used on patients who have TB is usually not involved in 
the transmission of M. tuberculosis, although transmission by 
contaminated bronchoscopes has been demonstrated (159,160). Guidelines 
for cleaning, disinfecting, and sterilizing equipment have been 
published (161,162). The rationale for cleaning, disinfecting, or 
sterilizing patient-care equipment can be understood more readily if 
medical devices, equipment, and surgical materials are divided into 
three general categories. These categories--critical, semicritical, and 
noncritical items--are defined by the potential risk for infection 
associated with their use (163,164).
    Critical items are instruments that are introduced directly into 
the bloodstream or into other normally sterile areas of the body (e.g., 
needles, surgical instruments, cardiac catheters, and implants). These 
items should be sterile at the time of use.
    Semicritical items are those that may come in contact with mucous 
membranes but do not ordinarily penetrate body surfaces (e.g., 
noninvasive flexible and rigid fiberoptic endoscopes or bronchoscopes, 
endotracheal tubes, and anesthesia breathing circuits). Although 
sterilization is preferred for these instruments, high-level 
disinfection that destroys vegetative microorganisms, most fungal 
spores, tubercle bacilli, and small nonlipid viruses may be used. 
Meticulous physical cleaning of such items before sterilization or 
high-level disinfection is essential.
    Noncritical items are those that either do not ordinarily touch the 
patient or touch only the patient's intact skin (e.g., crutches, 
bedboards, blood pressure cuffs, and various other medical 
accessories). These items are not associated with direct transmission 
of M. tuberculosis, and washing them with detergent is usually 
sufficient.
    Health-care facility policies should specify whether cleaning, 
disinfecting, or sterilizing an item is necessary to decrease the risk 
for infection. Decisions about decontamination processes should be 
based on the intended use of the item, not on the diagnosis of the 
patient for whom the item was used. Selection of chemical disinfectants 
depends on the intended use, the level of disinfection required, and 
the structure and material of the item to be disinfected.
    Although microorganisms are ordinarily found on walls, floors, and 
other environmental surfaces, these surfaces are rarely associated with 
transmission of infections to patients or HCWs. This is particularly 
true with organisms such as M. tuberculosis, which generally require 
inhalation by the host for infection to occur. Therefore, extraordinary 
attempts to disinfect or sterilize environmental surfaces are not 
indicated. If a detergent germicide is used for routine cleaning, a 
hospital-grade, EPA-approved germicide/disinfectant that is not 
tuberculocidal can be used. The same routine daily cleaning procedures 
used in other rooms in the facility should be used to clean TB 
isolation rooms, and personnel should follow isolation practices while 
cleaning these rooms. For final cleaning of the isolation room after a 
patient has been discharged, personal protective equipment is not 
necessary if the room has been ventilated for the appropriate amount of 
time (Table S3-1).

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Glossary

    This glossary contains many of the terms used in the guidelines, as 
well as others that are encountered frequently by persons who implement 
TB infection-control programs. The definitions given are not dictionary 
definitions but are those most applicable to usage relating to TB.
    Acid-fast bacilli (AFB): Bacteria that retain certain dyes after 
being washed in an acid solution. Most acid-fast organisms are 
mycobacteria. When AFB are seen on a stained smear of sputum or other 
clinical specimen, a diagnosis of TB should be suspected; however, the 
diagnosis of TB is not confirmed until a culture is grown and 
identified as M. tuberculosis.
    Adherence: Refers to the behavior of patients when they follow all 
aspects of the treatment regimen as prescribed by the medical provider, 
and also refers to the behavior of HCWs and employers when they follow 
all guidelines pertaining to infection control.
    Aerosol: The droplet nuclei that are expelled by an infectious 
person (e.g., by coughing or sneezing); these droplet nuclei can remain 
suspended in the air and can transmit M. tuberculosis to other persons.
    AIA: The American Institute of Architects, a professional body that 
develops standards for building ventilation.
    Air changes: The ratio of the volume of air flowing through a space 
in a certain period of time (i.e., the airflow rate) to the volume of 
that space (i.e., the room volume); this ratio is usually expressed as 
the number of air changes per hour (ACH).
    Air mixing: The degree to which air supplied to a room mixes with 
the air already in the room, usually expressed as a mixing factor. This 
factor varies from 1 (for perfect mixing) to 10 (for poor mixing), and 
it is used as a multiplier to determine the actual airflow required 
(i.e., the recommended ACH multiplied by the mixing factor equals the 
actual ACH required).
    Alveoli: The small air sacs in the lungs that lie at the end of the 
bronchial tree; the site where carbon dioxide in the blood is replaced 
by oxygen from the lungs and where TB infection usually begins.
    Anergy; The inability of a person to react to skin-test antigens 
(even if the person is infected with the organisms tested) because of 
immunosuppression.
    Anteroom: A small room leading from a corridor into an isolation 
room; this room can act as an airlock, preventing the escape of 
contaminants from the isolation room into the corridor.
    Area: A structural unit (e.g., a hospital ward or laboratory) or 
functional unit (e.g., an internal medicine service) in which HCWs 
provide services to and share air with a specific patient population or 
work with clinical specimens that may contain viable M tuberculosis 
organisms. The risk for exposure to M tuberculosis in a given area 
depends on the prevalence of TB in the population served and the 
characteristics of the environment.
    ASHRAE: The American Society of Heating, Refrigerating and Air-
Conditioning Engineers, Inc., a professional body that develops 
standards for building ventilation.
    Asymptomatic: Without symptoms, or producing no symptoms.
    Bacillus of Calmette and Guerin (BCG) vaccine: A TB vaccine used in 
many parts of the world.
    BACTEC: One of the most often used radiometric methods 
for detecting the early growth of mycobacteria in culture. It provides 
rapid growth (in 7-14 days) and rapid drug-susceptibility testing (in 
5-6 days). When BACTEC is used with rapid species 
identification methods, M. tuberculosis can be identified within 10-14 
days of specimen collection.
    Booster phenomenon: A phenomenon in which some persons (especially 
older adults) who are skin tested many years after infection with M. 
tuberculosis have a negative reaction to an initial skin test, followed 
by a positive reaction to a subsequent skin test. The second (i.e., 
positive) reaction is caused by a boosted immune response. Two-step 
testing is used to distinguish new infections from boosted reactions 
(see Two-step testing).
    Bronchoscopy: A procedure for examining the respiratory tract that 
requires inserting an instrument (a bronchoscope) through the mouth or 
nose and into the trachea. The procedure can be used to obtain 
diagnostic specimens.
    Capreomycin: An injectable, second-line anti-TB drug used primarily 
for the treatment of drug-resistant TB.
    Cavity: A hole in the lung resulting from the destruction of 
pulmonary tissue by TB or other pulmonary infections or conditions. TB 
patients who have cavities in their lungs are referred to as having 
cavitary disease, and they are often more infectious than TB patients 
without cavitary disease.
    Chemotherapy: Treatment of an infection or disease by means of oral 
or injectable drugs.
    Cluster: Two or more PPD skin-test conversions occurring within a 
3-month period among HCWs in a specific area or occupational group, and 
epidemiologic evidence suggests occupational (nosocomial) transmission.
    Contact: A person who has shared the same air with a person who has 
infectious TB for a sufficient amount of time to allow possible 
transmission of M. tuberculosis.
    Conversion, PPD: See PPD test conversion.
    Culture: The process of growing bacteria in the laboratory so that 
organisms can be identified.
    Cycloserine: A second-line, oral anti-TB drug used primarily for 
treating drug-resistant TB.
    Directly observed therapy (DOT): An adherence-enhancing strategy in 
which an HCW or other designated person watches the patient swallow 
each does of medication.
    DNA probe: A technique that allows rapid and precise identification 
of mycobacteria (e.g., M. tuberculosis and M. bovis) that are grown in 
culture. The identification can often be completed in 2 hours.
    Droplet nuclei: Microscopic particles (i.e., 1-5 m in 
diameter) produced when a person coughs, sneezes, shouts, or sings. The 
droplets produced by an infectious TB patient can carry tubercle 
bacilli and can remain suspended in the air for prolonged periods of 
time and be carried on normal air currents in the room.
    Drug resistance, acquired: A resistance to one or more anti-TB 
drugs that develops while a patient is receiving therapy and which 
usually results from the patient's nonadherence to therapy or the 
prescription of an inadequate regimen by a health-care provider.
    Drug resistance, primary: A resistance to one or more anti-TB drugs 
the exists before a patient is treated with the drug(s). Primary 
resistance occurs in persons exposed to and infected with a drug-
resistant strain of M. tuberculosis.
    Drug-susceptibility pattern: The anti-TB drugs to which the 
tubercle bacilli cultured from a TB patient are susceptible or 
resistant based on drug-susceptibility tests.
    Drug-susceptibility tests: Laboratory tests that determine whether 
tubercle bacilli cultured from a patient are susceptible or resistant 
to various anti-TB drugs.
    Ethambutol: A first-line, oral anti-TB drug sometimes used 
concomitantly with INH, rifampin, and pyrazinamide.
    Ethionamide: A second-line, oral anti-TB drug used primarily for 
treating drug-resistant TB.
    Exposure: The condition of being subjected to something (e.g., 
infectious agents) that could have a harmful effect. A person exposed 
to M. tuberculosis does not necessarily become infected (see 
Transmission).
    First-line drugs: The most often used anti-TB drugs (i.e., INH, 
rifampin, pyrazinamide, ethambutol, and streptomycin).
    Fixed room-air HEPA recirculation systems: Nonmobile devices or 
systems that remove airborne contaminants by recirculating air through 
a HEPA filter. These may be built into the room and permanently ducted 
or may be mounted to the wall or ceiling within the room. In either 
situation, they are fixed in place and are not easily movable.
    Fluorochrome stain: A technique for staining a clinical specimen 
with fluorescent dyes to perform a microscopic examination (smear) for 
mycobacteria. This technique is preferable to other staining techniques 
because the mycobacteria can be seen easily and the slides can be read 
quickly.
    Fomites: Linens, books, dishes, or other objects used or touched by 
a patient. These objects are not involved in the transmission of M. 
tuberculosis.
    Gastric aspirate: A procedure sometimes used to obtain a specimen 
for culture when a patient cannot cough up adequate sputum. A tube is 
inserted through the mouth or nose and into the stomach to recover 
sputum that was coughed into the throat and then swallowed. This 
procedure is particularly useful for diagnosis in children, who are 
often unable to cough up sputum.
    High-efficiency particulate air (HEPA) filter: A specialized filter 
that is capable of removing 99.97% of particles 0.3 
m in diameter and that may assist in controlling the 
transmission of M. tuberculosis. Filters may be used in ventilation 
systems to remove particles from the air or in personal respirators to 
filter air before it is inhaled by the person wearing the respirator. 
The use of HEPA filters in ventilation systems requires expertise in 
installation and maintenance.
    Human immunodeficiency virus (HIV) infection: Infection with the 
virus that causes acquired immunodeficiency syndrome (AIDS). HIV 
infection is the most important risk factor for the progression of 
latent TB infection to active TB.
    Immunosuppressed: A condition in which the immune system is not 
functioning normally (e.g., severe cellular immunosuppression resulting 
from HIV infection or immunosuppressive therapy). Immunosuppressed 
persons are at greatly increased risk for developing active TB after 
they have been infected with M. tuberculosis. No data are available 
regarding whether these persons are also at increased risk for 
infection with M. tuberculosis after they have been exposed to the 
organism.
    Induration: An area of swelling produced by an immune response to 
an antigen. In tuberculin skin testing or anergy testing, the diameter 
of the indurated area is measured 48-72 hours after the injection, and 
the result is recorded in millimeters.
    Infection: The condition in which organisms capable of causing 
disease (e.g., M. tuberculosis) enter the body and elicit a response 
from the host's immune defenses. TB infection may or may not lead to 
clinical disease.
    Infectious: Capable of transmitting infection. When persons who 
have clinically active pulmonary or laryngeal TB disease cough or 
sneeze, they can expel droplets containing M. tuberculosis into the 
air. Persons whose sputum smears are positive for AFB are probably 
infectious.
    Injectable: A medication that is usually administered by injection 
into the muscle (intramuscular [IM]) or the bloodstream (intravenous 
[IV]).
    Intermittent therapy: Therapy administered either two or three 
times per week, rather than daily. Intermittent therapy should be 
administered only under the direct supervision of an HCW or other 
designated person (see Directly observed therapy [DOT]).
    Intradermal: Within the layers of the skin.
    Isoniazid (INH): A first-line, oral drug used either done as 
preventive therapy or in combination with several other drugs to treat 
TB disease.
    Kanamycin: An injectable, second-line anti-TB drug used primarily 
for treatment of drug-resistant TB.
    Latent TB infection: Infection with M. tuberculosis, usually 
detected by a positive PPD skin-test result, in a person who has no 
symptoms of active TB and who is not infectious.
    Mantoux test: A method of skin testing that is performed by 
injecting 0.1 mL of PPD-tuberculin containing 5 tuberculin units into 
the dermis (i.e., the second layer of skin) of the forearm with a 
needle and syringe. This test is the most reliable and standardized 
technique for tuberculin testing (see Tuberculin skin test and Purified 
protein derivative [PPD]-tuberculin test).
    Multidrug-resistant tuberculosis (MDR-TB): Active TB caused by M. 
tuberculosis organisms that are resistant to more than one anti-TB 
drug; in practice, often refers to organisms that are resistant to both 
INH and rifampin with or without resistance to other drugs (see Drug 
resistance, acquired and Drug resistance, primary).
    M. tuberculosis complex: A group of closely related mycobacterial 
species that can cause active TB (e.g., M. tuberculosis, M. bovis, and 
M. africanum); most TB in the United States is caused by M. 
tuberculosis.
    Negative pressure: The relative air pressure difference between two 
areas in a healthcare facility. A room that is at negative pressure has 
a lower pressure than adjacent areas, which keeps air from flowing out 
of the room and into adjacent rooms or areas.
    Nosocomial: An occurrence, usually an infection, that is acquired 
in a hospital or as a result of medical care.
    Para-aminosalicylic acid: A second-line, oral anti-TB drug used for 
treating drug-resistant TB.
    Pathogenesis: The pathologic, physiologic, or biochemical process 
by which a disease develops.
    Pathogenicity: The quality of producing or the ability to produce 
pathologic changes or disease. Some nontuberculous mycobacteria are 
pathogenic (e.g., Mycobacterium kansasii), and others are not (.e.g., 
Mycobacterium phlei).
    Portable room-air HEPA recirculation units: Free-standing portable 
devices that remove airborne contaminants by recirculating air through 
a HEPA filter.
    Positive PPD reaction: A reaction to the purified protein 
derivative (PPD)-tuberculin skin test that suggests the person tested 
is infected with M. tuberculosis. The person interpreting the skin-test 
reaction determines whether it is positive on the basis of the size of 
the induration and the medical history and risk factors of the person 
being tested.
    Preventive therapy: Treatment of latent TB infection used to 
prevent the progression of latent infection to clinically active 
disease.
    Purified protein derivative (PPD)-tuberculin: A purified tuberculin 
preparation that was developed in the 1930s and that was derived from 
old tuberculin. The standard Mantoux test uses 0.1 mL of PPD 
standardized to 5 tuberculin units.
    Purified protein derivative (PPD)-tuberculin test: A method used to 
evaluate the likelihood that a person is infected with M. tuberculosis. 
A small dose of tuberculin (PPD) is injected just beneath the surface 
of the skin, and the area is examined 48-72 hours after the injection. 
A reaction is measured according to the size of the induration. The 
classification of a reaction as positive or negative depends on the 
patient's medical history and various risk factors (see Mantoux test).
    Purified protein derivative (PPD)-tuberculin test conversion: A 
change in PPD test results from negative to positive. A conversion 
within a 2-year period is usually interpreted as new M. tuberculosis 
infection, which carries an increased risk for progression to active 
disease. A booster reaction may be misinterpreted as a new infection 
(see Booster phenomenon and Two-step testing).
    Pyrazinamide: A first-line, oral anti-TB drug used in treatment 
regimens.
    Radiography: A method of viewing the respiratory system by using 
radiation to transmit an image of the respiratory system to film. A 
chest radiograph is taken to view the respiratory system of a person 
who is being evaluated for pulmonary TB. Abnormalities (e.g., lesions 
or cavities in the lungs and enlarged lymph nodes) may indicate the 
presence of TB.
    Radiometric method: A method for culturing a specimen that allows 
for rapid detection of bacterial growth by measuring production of 
CO2 by viable organisms; also a method of rapidly performing 
susceptibility testing of M. tuberculosis.
    Recirculation: Ventilation in which all or most of the air that is 
exhausted from an area is returned to the same area or other areas of 
the facility.
    Regimen: Any particular TB treatment plan that specifies which 
drugs are used, in what doses, according to what schedule, and for how 
long.
    Registry: A record-keeping method for collecting clinical, 
laboratory, and radiographic data concerning TB patients so that the 
data can be organized and made available for epidemiologic study.
    Resistance: The ability of some strains of bacteria, including M. 
tuberculosis, to grow and multiply in the presence of certain drugs 
that ordinarily kill them; such strains are referred to as drug-
resistant strains.
    Rifampin: A first-line, oral anti-TB drug that, when used 
concomitantly with INH and pyrazinamide, provides the basis for short-
course therapy.
    Room-air HEPA recirculation systems and units: Devices (either 
fixed or portable) that remove airborne contaminants by recirculating 
air through a HEPA filter.
    Second-line drugs: Anti-TB drugs used when the first-line drugs 
cannot be use (e.g., for drug-resistant TB or because of adverse 
reactions to the first-line drugs). Examples are cycloserine, 
ethionamide, and capreomycin.
    Single-pass ventilation: Ventilation in which 100% of the air 
supplied to an area is exhausted to the outside.
    Smear (AFB smear): A laboratory technique for visualizing 
mycobacteria. The specimen is smeared onto a slide and stained, then 
examined using a microscope. Smear results should be available within 
24 hours. In TB, a large number of mycobacteria seen on an AFB smear 
usually indicates infectiousness. However, a positive result is not 
diagnostic of TB because organisms other than M. tuberculosis may be 
seen on an AFB smear (e.g., nontuberculous mycobacteria).
    Source case: A case of TB in an infectious person who has 
transmitted M. tuberculosis to another person or persons.
    Source control: Controlling a contaminant at the source of its 
generation, which prevents the spread of the contaminant to the general 
work space.
    Specimen: Any body fluid, secretion, or tissue sent to a laboratory 
where smears and cultures for M. tuberculosis will be performed (e.g., 
sputum, urine, spinal fluid, and material obtained at biopsy).
    Sputum: Phlegm coughed up from deep within the lungs. If a patient 
has pulmonary disease, an examination of the sputum by smear and 
culture can be helpful in evaluating the organism responsible for the 
infection. Sputum should not be confused with saliva or nasal 
secretions.
    Sputum induction: A method used to obtain sputum from a patient who 
is unable to cough up a specimen spontaneously. The patient inhales a 
saline mist, which stimulates a cough from deep within the lungs.
    Sputum smear, positive: AFB are visible on the sputum smear when 
viewed under a microscope. Persons with a sputum smear positive for AFB 
are considered more infectious than those with smear-negative sputum.
    Streptomycin: A first-line, injectable anti-TB drug.
    Symptomatic: Having symptoms that may indicate the presence of TB 
or another disease (see Asymptomatic).
    TB case: A particular episode of clinically active TB. This term 
should be used only to refer to the disease itself, not the patient 
with the disease. By law, cases of TB must be reported to the local 
health department.
    TB infection: A condition in which living tubercle bacilli are 
present in the body but the disease is not clinically active. Infected 
persons usually have positive tuberculin reactions, but they have no 
symptoms related to the infection and are not infectious. However, 
infected persons remain at lifelong risk for developing disease unless 
preventive therapy is given.
    Transmission: The spread of an infectious agent from one person to 
another. The likelihood of transmission is directly related to the 
duration and intensity of exposure to M. tuberculosis (see Exposure).
    Treatment failures: TB disease in patients who do not respond to 
chemotherapy and in patients whose disease worsens after having 
improved initially.
    Tubercle bacilli: M. tuberculosis organisms.
    Tuberculin skin test: A method used to evaluate the likelihood that 
a person is infected with M. tuberculosis. A small dose of PPD-
tuberculin is injected just beneath the surface of the skin, and the 
area is examined 48-72 hours after the injection. A reaction is 
measured according to the size of the induration. The classification of 
a reaction as positive or negative depends on the patient's medical 
history and various risk factors (see Mantoux test, PPD test).
    Tuberculosis (TB): A clinically active, symptomatic disease caused 
by an organism in the M. tuberculosis complex (usually M. tuberculosis 
or, rarely, M. bovis or M. africanum).
    Two-step testing: A procedure used for the baseline testing of 
persons who will periodically receive tuberculin skin tests (e.g., 
HCWs) to reduce the likelihood of mistaking a boosted reaction for a 
new infection. If the initial tuberculin-test result is classified as 
negative, a second test is repeated 1-3 weeks later. If the reaction to 
the second test is positive, it probably represents a boosted reaction. 
If the second test result is also negative, the person is classified as 
not infected. A positive reaction to a subsequent test would indicate 
new infection (i.e., a skin-test conversion) in such a person.
    Ultraviolet germicidal irradiation (UVGI): The use of ultraviolet 
radiation to kill or inactivate microorganisms.
    Ultraviolet germicidal irradiation (UVGI) lamps: Lamps that kill or 
inactivate microorganisms by emitting ultraviolet germicidal radiation, 
predominantly at a wavelength of 254 nm (intermediate light waves 
between visible light and X-rays). UVGI lamps can be used in ceiling or 
wall fixtures or within air ducts of ventilation systems.
    Ventilation, dilution: An engineering control technique to dilute 
and remove airborne contaminants by the flow of air into and out of an 
area. Air that contains droplet nuclei is removed and replaced by 
contaminant-free air. If the flow is sufficient, droplet nuclei become 
dispersed, and their concentration in the air is diminished.
    Ventilation, local exhaust: Ventilation used to capture and remove 
airborne contaminants by enclosing the contaminant source (i.e., the 
patient) or by placing an exhaust hood close to the contaminant source.
    Virulence: The degree of pathogenicity of a micoorganism as 
indicated by the severity of the disease produced and its ability to 
invade the tissues of a host. M. tuberculosis is a virulent organism.

Index

Acid-fast bacilli smears (see Smears, AFB)
Acquired immunodeficiency syndrome (see HIV infection)
Administrative controls
Aerosol therapy
Aerosolized pentamidine
    Booths for administration
    Patient screening
    Risk for nonsocomial transmission of M. tuberculosis
    Tents for administration
AFB smears (see Smears, AFB)
AIDS (see HIV infection)
Air changes per hour (ACH)
    ASHRAE recommendations
    Determining
    Removal efficiencies
Airflow
    Monitoring direction
Ambulatory-care settings/areas
    Management of patients
American Conference of Governmental Industrial Hygienists, Inc. 
(ACGIH)
American Institute of Architects (AIA)
American Society of Heating, Refrigerating and Air-Conditioning 
Engineers, Inc. (ASHRAE)
Americans With Disabilities Act of 1990
Anergy testing
Anesthesia considerations
Anterooms
    Negative pressure for
Assignment of responsibility
Autopsy
    Risk for nonsocomial transmission of M. tuberculosis
Autopsy rooms
    HEPA filtration
    Respiratory protection
    UVGI
Bacteriology
    Collecting specimens
    Mixed mycobacterial infection
BCG (Bacille of Calmette and Guerin) vaccine
    Skin testing
    Vaccination
Bronchoscopy
    Ventilation
Chest radiography (see Diagnosis of TB)
Cluster (see PPD testing)
Cohorting
Community TB profile
Confidentiality
Contact investigation
Correctional facilities
Cough-inducing procedures
    Bronchoscopy
    General guidelines
    Home-health-care settings
    In ambulatory-care areas
    Patient recovery from
    Pentamidine, aerosolized
    Respiratory protection
    Risk for nonsocomial transmission of M. tuberculosis
Sputum induction
Counseling
    Immunocompromised workers
Culture methods
    Radiometric
Decontamination of patient-care equipment
    Supplement 5--Decontamination, disinfecting, and sterilizing of 
patient-care equipment
Dental care
Dental settings
    Infection-control precautions, TB
    PPD screening program
    Risk assessment
Diagnosis of TB
    Anergy testing
    Bacteriology (see Smears, AFB and Culture methods)
    Before aerosol therapy
    Bronchoscopy
    Chest radiograph
    Culturing
    DNA probes
    Fluorescent microscopy
    High-pressure liquid chromatography
    Hospitalized patients
    Index of suspicion
    Mantoux technique
    Medical history
    NAP test
    Nucleic acid probes
    PPD testing
    Radiometric culture
    Smears
    Supplement 2--Diagnosis and treatment of latent TB infection and 
active TB
    With anergy
    With immunocompromising conditions
    With simultaneous pulmonary infection
Directly observed therapy (DOT)
    Home-health-care settings
    Public health department
Discharge planning
Drug-resistant TB
Drug-susceptibility testing
    On initial isolates
    Radiometric methods
    Reporting to public health department
Education and training
Emergency medical services
    PPD screening program
    Respiratory protection
Emergency departments
    Management of patients
Endotracheal intubation
Engineering controls
Epidemiology, pathogenesis, and transmission of M. tuberculosis
Executive Summary
General ventilation
    Dilution and removal
    Facility airflow direction
    Mixing factor
    Negative pressure
    Recirculating systems
    Room airflow patterns
    Short-circuitingl
    Single-pass systems
Glossary
Health-care facility, definition
Health-care worker(s) (HCW[s])
    Confidentiality
    Counseling
    Risk for infection
    Risk for infection and disease in immunocompromised HCWs
    Job reassignment
    Definition
    Education and training
    Evaluating PPD conversions
    Evaluating positive PPD-test results
    Immunocompromised
    Preventive therapy
    Screening for active TB
    Screening for latent TB infection
    Training
    Workplace restrictions
    Active TB
    Latent TB infection
Health department
    Case notification
Health Resources and Services Administration
Heat wheel energy recovery units,
    HEPA filtration for
Hierarchy of controls
High-efficiency particulate (HEPA) filtration
    Autopsy rooms
    Disposable prefilters to extend life
    DOP penetration test
    Efficiency
    Enclosing booth use
    In ambulatory-care areas
    Individual room-air recirculation
    Installation, maintenance, and monitoring
    Longevity
    Pressure-sensing device to determine replacement need
    Recirculation of HEPA-filtered air within a room
    Evaluation
    Fixed room-air recirculation systems
    Portable room-air recirculation units
    Recirculation of HEPA-filtered air to other areas of facility
    Use when exhausting air to the outside
High-risk area
HIV infection
    Anergy testing
    Cell-mediated immunity, impaired
    Chest radiography
    Coinfection with M. tuberculosis
    Counseling HIV-infected HCWs
    Evaluation of PPD skin-test results
    Likelihood of infection after exposure to M. tuberculosis
    Progression from latent TB infection to active TB
    Smears, AFB
Home-health-care settings
    Cough-inducing procedures
    PPD screening program
    Respiratory protection
Hospices
Human immunodeficiency virus (see HIV infection)
Infection control
    Development of the TB infection-control plan
    Engineering controls
    Evaluation of engineering controls
    Fundamentals
    Hierarchy of control measures
    Observation of infection-control practices
Infection-control practices, evaluating effectiveness
Infectiousness
    Determining
    Factors determining
    In HIV-infected patients
    Length of, on therapy
    Monitoring
    Pediatric patients
    Supplement 1--Determining the infectiousness of a TB patient
    Noninfectiousness
Intensive-care units
Intermediate-risk area
Isolation practices
    Dental settings
    Discontinuation
    Facilitating patient adherence
    For multidrug-resistant TB
    Initiation
    Intensive-care units
    Keeping door to room closed
    Long-term-care facilities
    Minimizing access to room
    Patient education
    Pediatric patients
    Visitors
Isolation rooms
    Air changes per hour (ACH)
    Air exhaust
    Anteroom
    Grouping
    HEPA filtration
    Keeping door to room closed
    Negative pressure
    Number required
    Purpose
    Ultraviolet germicidal irradiation (UVGI)
Isoniazid (INH)
    During pregnancy
    Hepatitis
    Monitoring for adverse reactions
    Preventive therapy regimen
Laboratories
Local exhaust ventilation
    Discharge from booths, tents, and hoods
    Exterior devices
    Into TB isolation rooms
Long-term-care facilities
Low-risk area
Medical offices
Medical record review
Minimal-risk facility
Mycobacterium avium complex
National Institute for Occupational Safety and Health (NIOSH)
Negative pressure
    Alternate methods for achieving
    Definition
    Monitoring
    Pressure differential required
    Pressure-sensing devices
    Pressurizing the corridor
    Smoke-tube testing
    TB isolation rooms
    Tents and booths
Nosocomial transmission
    Factors promoting
Occupational groups
Occupational Safety and Health Administration (OSHA)
Operating rooms
    Anterooms
    Respiratory protection
    Ventilation
OSHA respiratory protection standard
Outbreaks of TB in health-care facilities
Patient-to-patient transmission
    Cohorting
    Investigating
Pediatric patients
Pneumocystis carinii
PPD reading
    Cut-points for risk groups
PPD testing
    Analysis of increased conversion rate
    Anergy
    BCG vaccination
    Booster phenomenon
    Cluster
    Contact investigation
    Conversions
    Dental settings
    Emergency medical services
    Evaluating PPD conversions
    Frequency
    HCWs with positive PPD tests
    Home-health-care settings
    Immunocompromised workers
    Interpretation of results
    Mantoux technique
    Occupational group
    Persons with HIV infection
    Positive-predictive value
    Pregnancy
    Recent PPD converters
    Recording results
    Self-reading results
    Staggered testing
    Two-step testing
Preventive therapy
    Drug-susceptibility testing
    For anergic persons
    Monitoring
    Pregnancy
    Regimens
Problem evaluation
    Active TB in HCWs
    Contact investigation
    Patient-to-patient transmission
    PPD test conversions in HCWs
Pubic health department
    Contact investigation
    Coordination
    Directly observed therapy (DOT)
    Discharge planning
    Providing assistance
    Reporting
Radiographs
Radiology department
Re-entrainment
Recommendations
    Aerosolized pentamidine
    AFB smears
    Analysis of PPD screening data
    Anergy testing
    Anterooms
    Autopsy rooms
    Bronchoscopy
    Case surveillance
    Community TB profile
    Contact investigation
    Correctional facilities
    Cough-inducing procedures
    Development of the TB infection-control plan
    Diagnosis
    Discharge planning
    Drug-susceptibility testing
    Emergency departments
    Emergency medical services
    Engineering controls
    Environmental/engineering evaluation
    HCW counseling
    HCW screening
    HEPA filtration
    Home-health-care settings
    Hospices
    Identification of patients who may have active TB
    Immunocompromised persons
    Infectiousness
    Initiation of TB isolation
    Initiation of treatment
    Isolation practices
    Correctional facilities
    Dental settings
    Discontinuation of
    Laboratories
    Long-term-care facilities
    Managing hospitalized patients
    Managing patients
    In ambulatory-care settings
    In correctional facilities
    In dental settings
    In emergency departments
    In emergency medical services settings
    In home-health-care settings
    In hospices
    In medical offices
    Mantoux technique
    Medical offices
    Multidrug-resistant tuberculosis (MDR-TB)
    Observation of infection-control practices
    Operating rooms
    Patient transport
    Periodic reassessment
    Preventive therapy for TB infection
    Problem evaluation
    Radiology department
    Radiometric culture
    Review of TB patient medical records
    Risk assessment
    Training
    Treatment for active TB
    Treatment for latent TB
    Triage
    UVGI
    UVGI maintenance
    Ventilation
    Waiting areas
    Workplace restrictions
Respiratory protection
    Cleaning
    Cough-inducing procedures
    Dental settings
    Effectiveness
    Emergency medical services
    Face-seal leakage
    Filter leakage
    Fit checking
    Fit testing
    Home-health-care settings
    Maintenance
    Medical screening
    Negative-pressure respirators
    NIOSH
    Operating rooms
    OSHA respiratory protection standard
    Performance criteria
    Positive-pressure respirators
    Respiratory protection program
    Reuse of respirators
    Storage
    Supplement 4--Respiratory protection
    Surgery
    Surgical masks for patients
    Training
    Visitors of TB patients
Respiratory protection program
    Elements
    Periodic evaluation
Risk assessment
    Case surveillance
    Community TB profile
    Elements of a risk assessment
    Examples
    How to perform
    Levels of risk
    Periodic reassessment
    Review of TB patient medical records
    Risk area definitions
    Who should conduct
Risk factors for disease progression
Risk groups
Signs and symptoms of active TB
Skin testing (see PPD testing)
Smears, AFB
Smoke-tube testing
Smoke tubes
Source control
Sputum induction
Surgical masks
    For patient transport
    For patients in ambulatory-care areas or emergency departments
    Visitors of TB patients
TB infection-control program
    Assigning supervisory responsibility
    Elements of a TB infection-control program
TB isolation rooms
    Achieving negative pressure
    Anterooms
    Cohorting
    Exhaust
    Grouping
    HEPA filtration
    In ambulatory-care areas
    Negative pressure
    Purpose
    Ventilation
TB patient scheduling
Tissues
    For hospitalized patients
    For patients in ambulatory-care areas or emergency departments
    Home-health-care settings
Transporting TB patients
Treatment for TB
    Adherence
    Directly observed therapy (DOT)
    Dosage recommendations for children and adults
    Drug susceptibility
    For active TB
    For latent TB infection
    During pregnancy
    For active TB
    For latent TB infection
    Initiation of
    Preventive therapy
    Regimen options for children and adults
    Supplement 2--Diagnosis and treatment for latent TB infection 
and active TB
    Treatment for active TB
Triage
Tuberculin skin test (see PPD testing)
Ultraviolet germicidal irradiation (UVGI)
    Activation of HIV gene promoters
    Applications
    Autopsy rooms
    Carcinogenicity
    Definition
    Determining maximum permissible exposure times
    Duct irradiation
    Educating HCWs
    Effectiveness
    Exposure criteria for UV radiation
    HCW training issues
    In ambulatory-care settings
    Installation
    Labelling and posting caution signs
    Limitations
    Maintenance
    Monitoring
    Obtaining consultation before installation
    Precautions
    Recommended exposure limits (RELs)
    Safety issues
    Upper-room air irradiation
    UV radiation, definition
Ventilation
    Air changes per hour (ACH)
    Airflow patterns
    Ambulatory-care areas
    Anterooms
    Autopsy rooms
    Correctional facilities
    Dilution and removal
    Direction of airflow
    Discharge from booths, tents, and hoods
    Emergency departments
    Emergency medical services
    Enclosing devices
    Engineers
    Evaluation
    Exhaust
    General ventilation
    HEPA filter installation, maintenance, and monitoring
    Home-health-care settings
    Hospices
    Local exhaust ventilation
    Discharge exhaust
    Enclosing devices
    Exterior devices
    Maintenance
    Monitoring
    Mixing factor
    Negative pressure
    Operating rooms
    Periodic evaluation
    Positive-pressure rooms
    Pressure-sensing devices
    Pressurizing the corridor to induce negative pressure
    Radiology department
    Rates (see Air changes per hour [ACH])
    Recirculation of HEPA filtered air
    Fixed
    Portable
    Re-entrainment
    Short-circuiting
    Single-pass system
    Source control methods
    Stagnation
    Supplement 3--Engineering issues in TB control
    TB isolation rooms
    Tents and booths (see Local exhaust ventilation)
    Treatment rooms
    Ventilation rates
    Waiting-room areas
Very low-risk area or facility
Visitors
    Contact investigation
    Pediatric patients
    Protection against UVGI
    Respiratory protection for
Waiting-room areas
Workplace reassignment
Workplace restrictions
    Active TB
    Extrapulmonary TB
    Latent TB infection
    Nonadherence to preventive therapy
    Nonadherence to treatment
    Return to work

List of Tables

Table 1. Elements of a risk assessment for tuberculosis (TB) in 
health-care facilities
Table 2. Elements of a tuberculosis (TB) infection-control program
Table 3. Characteristics of an effective tuberculosis (TB) 
infection-control program
Table 4. Examples of potential problems that can occur when 
identifying or isolating patients who may have infectious 
tuberculosis (TB)
Table S2-1. Summary of interpretation of purified protein derivative 
(PPD)-tuberculin skin-test results
Table S2-2. Regimen options for the treatment of tuberculosis (TB) 
in children and adults
Table S2-3. Dosage recommendations for the initial treatment of 
tuberculosis in children and adults
Table S3-1. Air changes per hour (ACH) and time in minutes required 
for removal efficiencies of 90%, 99%, and 99.9% of airborne 
contaminants
Table S3-2. Hierarchy of ventilation methods for tuberculosis (TB) 
isolation rooms and treatment rooms
Table S3-3. Maximum permissible exposure times for selected values 
of effective irradiance

List of Figures

Figure 1. Protocol for conducting a tuberculosis (TB) risk 
assessment in a health-care facility
Figure 2. Protocol for investigating purified protein derivative 
(PPD)-tuberculin skin-test conversions in health-care workers (HCWs)
Figure S3-1. An enclosing booth designed to sweep air past a patient 
who has active tuberculosis and entrap the infectious droplet nuclei 
in a high-efficiency particulate air (HEPA) filter
Figure S3-2. Room airflow patterns designed to provide mixing of air 
and prevent passage of air directly from the air supply to the 
exhaust
Figure S3-3. Smoke-tube testing and anemometer placement to 
determine the direction of airflow into and out of a room
Figure S3-4. Cross-sectional view of a room showing the location of 
negative pressure measurement
Figure S3-5. Fixed, ducted room-air recirculation system using a 
high-efficiency particulate air (HEPA) filter inside an air duct
Figure S3-6. Fixed ceiling-mounted room-air recirculation system 
using a high-efficiency particulate air (HEPA) filter
Figure S3-7. Air recirculation zone created by wind blowing over a 
building

[FR Doc. 94-26598 Filed 10-27-94; 8:45 am]
BILLING CODE 4163-18-P