[Federal Register Volume 59, Number 22 (Wednesday, February 2, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-2178]


[[Page Unknown]]

[Federal Register: February 2, 1994]


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Part II





Department of Health and Human Services





_______________________________________________________________________



Centers for Disease Control and Prevention



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Draft Guideline for Prevention of Nosocomial Pneumonia; Notice of 
Comment Period
DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

 

Draft Guideline for Prevention of Nosocomial Pneumonia: Part 1. 
``Issues on Prevention of Nosocomial Pneumonia--1994'' and Part 2. 
``Recommendations for Prevention of Nosocomial Pneumonia''; Notice of 
Comment Period

AGENCY: Centers for Disease Control and Prevention (CDC), Public Health 
Service (PHS), Department of Health and Human Services (DHHS).

ACTION: Notice.

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SUMMARY: This notice is a request for review and comment of the draft 
Guideline for Prevention of Nosocomial Pneumonia. The Guideline 
consists of two parts entitled ``Issues on Prevention of Nosocomial 
Pneumonia--1994,'' and ``Recommendations for Prevention of Nosocomial 
Pneumonia,'' prepared by the Hospital Infection Control Practices 
Advisory Committee (HICPAC) and the National Center for Infectious 
Diseases (NCID), CDC.

DATES: Written comments on the draft document must be received on or 
before April 4, 1994.

ADDRESSES: Comments on this document should be submitted in writing to 
the CDC, Attention: Pneumonia Guideline Information Center, Mailstop 
A07, 1600 Clifton Road, NE., Atlanta, Georgia 30333. To order copies of 
the Federal Register containing the document, contact the U.S. 
Government Printing Office, Order and Information Desk, Washington, DC 
20402-9329, at (202) 783-3238. Specify the date of the issue requested 
and stock number 069-001-000-70-0. See page II of the Federal Register 
for additional ordering and cost information. In addition, the Federal 
Register may be viewed and photocopied at most libraries designated as 
U.S. Government Depository Libraries and at many other public and 
academic libraries that receive the Federal Register throughout the 
country. The order-desk operator can tell you the location of the U.S. 
Government Depository Library nearest you.

FOR FURTHER INFORMATION CONTACT: The Pneumonia Guideline Information 
Center, (404) 332-2569.

SUPPLEMENTARY INFORMATION: This document updates and replaces the 
previously published CDC Guideline for the Prevention of Nosocomial 
Pneumonia. Emphasis is placed on bacterial pneumonias, including gram-
negative bacillary pneumonias and Legionnaires' disease; pneumonia due 
to Aspergillus spp.; and lower respiratory tract infections caused by 
respiratory syncytial and influenza viruses. Part I, ``Issues on 
Prevention of Nosocomial Pneumonia--1994,'' was prepared by staff of 
NCID, CDC, and provides the background for the HICPAC-consensus 
recommendations contained in Part II, ``Recommendations for Prevention 
of Nosocomial Pneumonia.''
    HICPAC was established in 1991 to provide advice and guidance to 
the Secretary, DHHS; the Assistant Secretary for Health; the Director, 
CDC; and the Director, NCID, regarding the practice of hospital 
infection control and strategies for surveillance, prevention, and 
control of nosocomial infections in U.S. hospitals. The committee also 
advises the CDC on periodic updating of guidelines and other policy 
statements regarding prevention of nosocomial infections.
    The Guideline for Prevention of Nosocomial Pneumonia is the first 
of a series of CDC guidelines being revised by HICPAC and NCID, CDC.

    Dated: January 25, 1994.
Walter R. Dowdle,
Deputy Director, Centers for Disease Control and Prevention (CDC).

GUIDELINE FOR PREVENTION OF NOSOCOMIAL PNEUMONIA

Second Edition

Table of Contents

Executive Summary

Introduction

Part I. Issues on Prevention of Nosocomial Pneumonia--1994

Bacterial Pneumonia

I. Etiologic Agents
II. Diagnosis
III. Epidemiology
IV. Pathogenesis
V. Risk Factors and Control Measures
    A. Oropharyngeal, Tracheal, and Gastric Colonization
    B. Aspiration of Oropharyngeal and Gastric Flora
    C. Mechanically Assisted Ventilation
    D. Cross-Colonization Via Hands of Personnel
    E. Contamination of Devices Used on the Respiratory Tract
    1. Mechanical Ventilators and Anesthesia Machines
    2. Humidifiers, Breathing Circuits, and Heat-Moisture Exchangers
    3. Large-Volume Nebulizers
    4. Small-Volume Medication Nebulizers
    5. Suction Catheters, Resuscitation Bags, Oxygen Analyzers, and 
Ventilator Spirometers
    F. Thoraco-Abdominal Surgical Procedures
    G. Other Prophylactic Measures
    1. Vaccination of Patients
    2. Prophylaxis With Systemic Antimicrobial Agents
    3. Kinetic Therapy for the Immobilized State

Legionnaires' Disease

I. Epidemiology
II. Diagnosis
III. Modes of Transmission
IV. Definition of Nosocomial Legionnaires' Disease
V. Prevention and Control Measures
    A. Prevention of Legionnaires' Disease in Hospitals With No 
Identified Cases (Primary Prevention)
    B. Prevention of Legionnaires' Disease in Hospitals With 
Identified Cases (Secondary Prevention)

Aspergillosis

I. Epidemiology
II. Pathogenesis
III. Diagnosis
IV. Risk Factors and Control Measures

Viral Pneumonias

RSV Infection

I. Epidemiology
II. Diagnosis
III. Modes of Transmission
IV. Control Measures

Influenza

I. Epidemiology
II. Diagnosis
III. Prevention and Control Measures

Part II. Recommendations for Prevention of Nosocomial Pneumonia

Introduction

Prevention and Control of Bacterial Pneumonia

I. Staff Education and Infection Surveillance
    A. Staff Education
    B. Surveillance
II. Interruption of Transmission of Microorganisms
    A. Sterilization or Disinfection, and Maintenance of Equipment 
and Devices
    1. General Measures
    2. Mechanical Ventilators, Anesthesia Machines and Circle 
Systems, and Pulmonary-Function Testing Equipment
    3. Ventilator Circuits With Humidifiers
    4. Ventilator Circuits With Hygroscopic Condenser-Humidifiers or 
Heat-Moisture Exchangers
    5. Wall Humidifiers
    6. Small-Volume Medication Nebulizers: ``In-Line'' and Hand-Held 
Nebulizers
    7. Large-volume nebulizers and mist tents
    8. Other Devices
    B. Interruption of Person-to-Person Transmission of Bacteria
    1. Handwashing
    2. Barrier Precautions
    3. Care of Patients with Tracheostomy
    4. Suctioning of Respiratory Tract Secretions
III. Modifying Host Risk for Infection
    A. Precautions for Prevention of Endogenous Pneumonia
    1. Prevention of Aspiration
    2. Prevention of Gastric Colonization
    B. Prevention of Postoperative Pneumonia
    C. Other Prophylactic Procedures for Pneumonia
    1. Vaccination of Patients
    2. Systemic Antimicrobial Prophylaxis
    3. Use of Rotating ``Kinetic'' Beds

Prevention and Control of Legionnaires' Disease

I. Staff Education and Infection Surveillance
    A. Staff Education
    B. Surveillance
II. Interruption of Transmission of Legionella spp.
    A. Primary Prevention (Preventing Nosocomial Legionnaires' 
Disease when No Cases have been Documented)
    1. Nebulization and Other Devices
    2. Cooling Towers
    3. Water-Distribution System
    B. Secondary Prevention (Response to Identification of 
Laboratory-Confirmed Nosocomial Legionellosis)

Prevention and Control of Nosocomial Pulmonary Aspergillosis

I. Staff Education and Infection Surveillance
    A. Staff Education
    B. Surveillance
II. Interruption of Transmission of Aspergillus spp. Spores
    A. Planning New Specialized-Care Units for High-Risk Patients
    B. In Existing Facilities with no Cases of Nosocomial 
Aspergillosis
    C. When a Case of Nosocomial Aspergillosis Occurs
III. Modifying Host Risk for Infection

Prevention and Control of Respiratory Syncytial Virus (RSV)

I. Staff Education and Infection Surveillance
    A. Staff Education
    B. Surveillance
II. Interruption of Transmission of RSV
    A. Prevention of Person-to-Person Transmission
    1. Primary Measures for Contact Isolation
    a. Handwashing
    b. Gloving
    c. Gowning
    d. Staffing
    e. Limiting Visitors
    2. Control of RSV Outbreaks
    a. Use of Private Room, Cohorting, and Patient-Screening
    b. Personnel Cohorting
    c. Postponing Patient Admission
    d. Wearing Eye-Nose Goggles

Prevention and Control of Influenza

I. Staff Education and Infection Surveillance
    A. Staff Education
    B. Surveillance
II. Modifying Host Risk for Infection
    A. Vaccination
    1. Patients
    2. Personnel
    B. Use of Antiviral Agents
III. Interruption of (Person-to-Person) Transmission
IV. Control of Influenza Outbreaks
    A. Determining the Outbreak Strain
    B. Vaccination of Patients and Personnel
    C. Amantadine or Rimantadine Administration
    D. Interruption of (Person-to-Person) Transmission

Table 1. Microorganisms Isolated from Respiratory Tract Specimens 
Obtained by Various Representative Methods from Adult Patients with 
a Diagnosis of Nosocomial Pneumonia
Table 2. Controlled Studies on Nosocomial Lower Respiratory Tract 
Infections and Other Associated Outcomes of Selective 
Decontamination of the Digestive Tract in Adult Patients with 
Mechanically Assisted Ventilation
Table 3. Risk Factors and Suggested Infection Control Measures for 
Prevention of Nosocomial Pneumonia

Figure 1. Pathogenesis of Nosocomial Bacterial Pneumonia

Appendix A. Semicritical Items Used on the Respiratory Tract
Appendix B. Maintenance Procedures to Decrease Survival and 
Multiplication of Legionella spp. in Potable-Water Distribution 
Systems
Appendix C. Culturing Environmental Specimens for Legionella spp.
Appendix D. Procedure for Cleaning Cooling Towers and Related 
Equipment to Prevent Legionellosis

References

Executive Summary

    This document updates and replaces the previously published CDC 
Guideline for Prevention of Nosocomial Pneumonia (Infection Control 
1982;3:327-33, Resp Care 1983;28:221-32, and Am J Infect Control 
1983;11230-9). The revised guideline is designed to reduce the 
incidence of nosocomial pneumonia and provides the rationale (in Part 
I) for the recommendations (in Part II) considered prudent by consensus 
of the members of HICPAC. A working draft of the guideline has been 
reviewed by experts in infection control, pulmonology, respiratory 
therapy, anesthesiology, internal medicine, and pediatrics. However, 
all recommendations in the guideline may not reflect the opinions of 
all reviewers.
    Pneumonia is the second most common nosocomial infection in the 
United States and is associated with substantial morbidity and 
mortality. Most patients with nosocomial pneumonia are those with 
extremes of age, severe underlying disease, immunosuppression, 
depressed sensorium, cardiopulmonary disease, and thoraco-abdominal 
surgery. Although patients with mechanically assisted ventilation do 
not comprise a major proportion of patients with nosocomial pneumonia, 
they have the highest risk of developing the infection.
    Most bacterial nosocomial pneumonias occur by aspiration of 
bacteria colonizing the oropharynx or upper gastrointestinal tract of 
the patient. Intubation and mechanical ventilation greatly increase the 
risk of nosocomial bacterial pneumonia because they alter first-line 
patient defenses. Pneumonias due to Legionella spp., Aspergillus spp., 
and influenza virus are often caused by inhalation of contaminated 
aerosols. Respiratory syncytial virus (RSV) infection usually follows 
viral inoculation of the conjunctivae or nasal mucosa by contaminated 
hands.
    Traditional preventive measures for nosocomial pneumonia include 
decreasing aspiration by the patient, preventing cross-contamination or 
colonization via hands of personnel, appropriate disinfection or 
sterilization of respiratory-therapy devices, use of available vaccines 
to protect against particular infections, and education of hospital 
staff and patients. New measures under investigation involve reducing 
oropharyngeal and gastric colonization by pathogenic microorganisms.

Introduction

    The Guideline for Prevention of Nosocomial Pneumonia is intended 
for use by personnel who are responsible for surveillance and control 
of infections in acute-care hospitals. The guideline may not be 
applicable in long-term care facilities because of the unique 
characteristics of these settings.
    The revised guideline addresses common problems encountered by 
infection-control practitioners regarding the prevention and control of 
nosocomial pneumonia in U.S. hospitals. Sections on the prevention of 
bacterial pneumonia in mechanically ventilated and/or critically ill 
patients, care of respiratory-therapy devices, prevention of cross-
contamination, and prevention of viral lower respiratory-tract 
infections, such as respiratory syncytial virus (RSV) and influenza 
infections, have been expanded and updated. New sections on 
Legionnaires' disease and pneumonia due to Aspergillus spp. have been 
added. Lower respiratory tract infection due to Mycobacterium 
tuberculosis is not addressed in this document; it is covered in 
separate guidelines.\1\*
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    *Footnotes to appear at end of docket.
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    Part I, Issues for Prevention of Nosocomial Pneumonia--1994, can be 
an important resource for educating healthcare workers regarding 
prevention and control of nosocomial respiratory tract infections. 
Because education of healthcare workers is the cornerstone of an 
effective infection control program, hospitals should give high 
priority to continuing infection control educational programs for these 
staff members.

PART I. ISSUES ON PREVENTION OF NOSOCOMIAL PNEUMONIA--1994

BACTERIAL PNEUMONIA

I. Etiologic Agents

    The reported distribution of etiologic agents causing nosocomial 
pneumonia varies between hospitals because of differences in patient 
populations and diagnostic methods employed.2-11 In general, 
however, bacteria have been the most frequently isolated 
pathogens.2-7,10,12-14 Schaberg et al. reported that in 1986-1989, 
aerobic bacteria comprised at least 73%, and fungi 4%, of isolates from 
sputum and tracheal aspirates of cases at the University of Michigan 
Hospitals and hospitals participating in the National Nosocomial 
Infection Surveillance (NNIS); very few anaerobic bacteria and no 
viruses were reported, probably because anaerobic and viral cultures 
were not performed routinely in the reporting hospitals (Table 
1).4 Similarly, cultures of bronchoscopic specimens from 
mechanically ventilated patients with pneumonia have rarely yielded 
anaerobes.6-8,10,12,15,16 Only the report by Bartlett, which was 
based mainly on cultures of transtracheal aspirates in patients not 
receiving mechanically assisted ventilation, showed a predominance of 
anaerobes.5
    Nosocomial bacterial pneumonias are frequently 
polymicrobial,5,8,10,12,13,16-20 and gram-negative bacilli are the 
usual predominant organisms (Table 1);2-7,10,12-14 however, 
Staphylococcus aureus (especially methicillin-resistant S. 
aureus)6,8,11,16,21 and other gram-positive cocci, including 
Streptococcus pneumoniae,6,8 have recently emerged as significant 
isolates;15 and Haemophilus influenza has been isolated from 
mechanically ventilated patients with pneumonia that occurs within 48-
96 hours after intubation.4-6,13,16,22 In NNIS hospitals, 
Pseudomonas aeruginosa, Enterobacter sp., Klebsiella pneumoniae, 
Escherichia coli, Serratia marcescens, and Proteus spp. comprised 50% 
of the isolates from cultures of respiratory tract specimens of 
patients for whom nosocomial pneumonia was diagnosed by using clinical 
criteria; S. aureus accounted for 16%, and H. influenzae, for 6% (Table 
1).4 Fagon and co-workers reported that gram-negative bacilli were 
present in 75% of quantitative cultures of protected-specimen brushings 
(PSB) from patients who had received mechanically assisted ventilation 
and acquired nosocomial pneumonia; 40% were polymicrobial.6 In the 
report by Torres et al., 20% of pathogens recovered from cultures of 
PSB, blood, pleural fluid, or percutaneous lung aspirate were gram-
negative bacilli in pure culture, and 17% were polymicrobial; however, 
54% of specimens did not yield any microorganism, probably because of 
receipt of antibiotics by patients.7

II. Diagnosis

    The diagnosis of nosocomial bacterial pneumonia has been 
difficult.8,9,17,23-32 Frequently, the criteria for diagnosis have 
been fever, cough, and development of purulent sputum, in combination 
with radiologic evidence of a new or progressive pulmonary infiltrate, 
a suggestive Gram's stain, and cultures of sputum, tracheal aspirate, 
pleural fluid, or blood.4,5,23,25,33-36 Although clinical criteria 
together with cultures of sputum or tracheal specimens may be sensitive 
for bacterial pathogens, they are highly nonspecific, especially in 
patients with mechanically assisted ventilation;9,10,13-16,19,24-
26,29,31,37-42 on the other hand, cultures of blood or pleural fluid 
have very low sensitivity.9,19,20,43
    Because of these problems, a group of investigators recently 
formulated consensus recommendations for standardization of methods to 
diagnose pneumonia in clinical research studies of ventilator-
associated pneumonia.44-46 These methods involve bronchoscopic 
techniques, e.g., quantitative culture of PSB,6,8-
10,14,16,27,31,38,41,47,48 BAL,8,13,41,47,49-54 and pBAL.15 
The reported sensitivities and specificities of these methods have 
ranged between 70% to 100% and 60% to 100%, respectively, depending on 
the tests or diagnostic criteria they were compared with. Because these 
techniques are invasive, they may cause complications such as 
hypoxemia, bleeding, or arrhythmia.9,14,42,44,52,55,56 In 
addition, the sensitivity of the PSB procedure may decrease in patients 
receiving antibiotic therapy.10,14,27 Nonbronchoscopic (NB) 
procedures, e.g., NB-pBAL13,27,57,58 or NB-PSB,14 which 
utilize blind catheterization of the distal airways, have been 
developed recently; however, they have not been extensively evaluated. 
Although the use of bronchoscopic and nonbronchoscopic diagnostic tests 
can be a major step in better defining the epidemiology of nosocomial 
pneumonia especially in mechanically ventilated patients, further 
studies are needed to determine their applicability in daily clinical 
practice.

III. Epidemiology

    NNIS reports that pneumonias (diagnosed on the basis of the CDC 
surveillance definition of nosocomial pneumonia) and surgical-wound 
infections account for approximately 15% each of all hospital-
associated infections and are the second most common nosocomial 
infections after that of the urinary tract.3 In 1984, the overall 
incidence of lower respiratory tract infection was 6 per 1,000 
discharged patients.3 The incidence ranged from 4.2 to 7.7 per 
1,000 discharged patients for nonteaching and university-affiliated 
hospitals, respectively, probably reflecting institutional differences 
in the level of patients' risk for acquiring nosocomial pneumonia.
    Nosocomial bacterial pneumonia often has been identified as a 
postoperative infection.59,60 In the Study of the Efficacy of 
Nosocomial Infection Control in the 1970s, 75% of reported cases of 
nosocomial bacterial pneumonia occurred in patients who had had a 
surgical operation; the risk was 38 times greater for thoracoabdominal 
procedures than for those involving other body sites.60 More 
recent epidemiologic studies, including NNIS studies, have identified 
other subsets of patients at high risk of developing nosocomial 
bacterial pneumonia: Patients with endotracheal intubation and/or 
mechanically assisted ventilation, depressed level of consciousness 
(particularly those with closed-head injury), prior episode of a large-
volume aspiration, or underlying chronic lung disease, and patients >70 
years of age. Other risk factors include 24-hour ventilator-circuit 
changes, fall-winter season, stress-bleeding prophylaxis with 
cimetidine with or without antacid, presence of a nasogastric tube, 
severe trauma, and recent bronchoscopy.7,34,35,61-69
    Recently, NNIS stratified the incidence density of nosocomial 
pneumonia by patients' use of mechanical ventilator and type of 
intensive care unit (ICU). From 1986 to 1990, the median rate of 
ventilator-associated pneumonia per 1,000 ventilator-days ranged from 
4.7 in pediatric ICUs to 34.4 in burn ICUs.63 In contrast, the 
median rate of nonventilator-associated pneumonia per 1000 ICU-days 
ranged from 0 in pediatric and respiratory ICUs to 3.2 in trauma ICUs.
    Nosocomial pneumonia has been associated with high fatality rates. 
Crude mortality rates of 20%-50% and attributable mortality rates of 
30%-33% have been reported; in one study, pneumonia comprised 60% of 
all deaths due to nosocomial infections.18,35,70-75 Patients 
receiving mechanically assisted ventilation have higher mortality rates 
than patients not receiving ventilation support; however, other 
factors, such as a patient's underlying disease(s) and organ failure, 
are stronger predictors of death in patients with pneumonia.34
    Pneumonia-associated morbidity has not been evaluated in recent 
years. Past studies, however, have shown that pneumonia could prolong 
hospitalization by 4-9 days.74-77 A conservative estimate of the 
direct cost of excess hospital stay due to pneumonia is $1.1 billion a 
year for the nation.78 Because of its reported frequency, 
associated high fatality rate, and attendant costs, nosocomial 
pneumonia is a major infection control problem.

IV. Pathogenesis

    Bacteria may invade the lower respiratory tract by aspiration of 
oropharyngeal organisms, inhalation of aerosols containing bacteria, or 
less frequently, by hematogenous spread from a distant body site 
(Figure 1). In addition, bacterial translocation from the 
gastrointestinal tract has been recently hypothesized as a mechanism 
for infection. Of these routes, aspiration is believed to be the most 
important for both nosocomial and community-acquired pneumonia.
    In radioisotope-tracer studies of healthy adults, 45% were found to 
aspirate during sleep.79 Persons with abnormal swallowing, such as 
those who have depressed consciousness, respiratory tract 
instrumentation and/or mechanically assisted ventilation, 
gastrointestinal tract instrumentation or diseases, or have just 
undergone surgery, are particularly likely to 
aspirate.7,34,35,60,80
    The high incidence of gram-negative bacillary pneumonia in 
hospitalized patients appears to be the result of factors that promote 
colonization of the pharynx by gram-negative bacilli and the subsequent 
entry of these organisms into the lower respiratory tract.33,81-84 
Whereas aerobic gram-negative bacilli are recovered infrequently or are 
found in small numbers in pharyngeal cultures of healthy 
persons,81,85 colonization dramatically increases in patients with 
coma, hypotension, acidosis, azotemia, alcoholism, diabetes mellitus, 
leukocytosis, leukopenia, pulmonary disease, nasogastric or 
endotracheal tubes in place, and in patients given antimicrobial 
agents.33,84,86,87
    Oropharyngeal or tracheobronchial colonization by gram-negative 
bacilli begins with the adherence of the microorganisms to the host's 
epithelial cells.83,88-90 Adherence may be affected by multiple 
factors related to the bacteria (presence of pili, cilia, capsule, or 
production of elastase or mucinase), host cell (surface proteins and 
polysaccharides), and environment (pH and presence of mucin in 
respiratory secretions).82,83,88,91-100 The exact interactions 
among these factors have not been fully elucidated, but studies 
indicate that certain substances, such as fibronectin, can inhibit the 
adherence of gram-negative bacilli to host cells.91,93,101 
Conversely, certain conditions, such as malnutrition, severe illness, 
or post-operative state, can increase adherence of gram-negative 
bacteria.82,91,95,100,102
    Besides the oropharynx, the stomach has been postulated to be an 
important reservoir of organisms that cause nosocomial 
pneumonia.34,103-107 The stomach's role may vary depending on the 
patient's underlying conditions and on prophylactic or therapeutic 
interventions.22,104,108-111 In healthy persons, few bacteria 
entering the stomach survive in the presence of hydrochloric acid at 
pH<2.112,113 However, when gastric pH increases from the normal 
levels to >4, microorganisms are able to multiply to high 
concentrations in the stomach.110,112,114-116 This can occur in 
patients with advanced age,114 achlorhydria,112 ileus, or 
upper gastrointestinal disease, and in patients receiving enteral 
feeding, antacids, or histamine-2 [H-2] 
antagonists.104,110,111,116-118 The contribution of other factors, 
such as duodeno-gastric reflux and the presence of bile, to gastric 
colonization in patients with impaired intestinal motility has been 
suggested and needs further investigation.109
    Bacteria can also gain entry into the lower respiratory tract of 
hospitalized patients through inhalation of aerosols generated 
primarily by contaminated respiratory-therapy or anesthesia-breathing 
equipment.119-122 Outbreaks related to the use of respiratory-
therapy equipment have been associated with contaminated nebulizers, 
which are humidification devices that produce large amounts of aerosol 
droplets <4m via ultrasound, spinning disk, or the Venturi 
mechanism.119,122,123 When the fluid in the reservoir of a 
nebulizer becomes contaminated with bacteria, the aerosol produced may 
contain high concentrations of bacteria that can be deposited deep in 
the patient's lower respiratory tract.119,123,124 Because 
endotracheal and tracheal tubes provide direct access to the lower 
respiratory tract, contaminated aerosol inhalation is particularly 
hazardous for intubated patients. In contrast to nebulizers, bubble-
through or wick humidifiers mainly increase the water-vapor (or 
molecular-water) content of inspired gases. Although heated bubble-
through humidifiers generate aerosol droplets, they do so in quantities 
that may not be clinically significant;120,125 wick humidifiers do 
not generate aerosols.
    Rarely, bacterial pneumonia can result from hematogenous spread of 
infection to the lung from another infection site, e.g., pneumonia 
resulting from purulent phlebitis or right-sided endocarditis. Another 
mechanism, translocation of bacteria via the passage of viable bacteria 
from the lumen of the gastrointestinal tract through epithelial mucosa 
to the mesenteric lymph nodes and to the lung has been shown in animal 
models.126 Translocation is postulated to occur in patients with 
immunosuppression, cancer or burns;126 however data are lacking 
regarding this mechanism in humans.127

V. Risk Factors and Control Measures

    Several large studies have examined potential risk factors for 
nosocomial bacterial pneumonia (Table 
3).7,\\34,\\35,\\128,\\129 Although specific 
risk factors may differ between study populations, they can be grouped 
into the following general categories: (1) Host factors such as 
extremes of age and severe underlying conditions, including 
immunosuppression; (2) factors, such as admission to the ICU, 
underlying chronic lung disease, or coma, that enhance colonization of 
the oropharynx and/or stomach by microorganisms; (3) conditions 
favoring aspiration or reflux, including endotracheal intubation or 
insertion of nasogastric tube; (4) conditions requiring prolonged use 
of mechanical ventilatory support with exposure to contaminated 
respiratory equipment and/or contact with colonized hands of healthcare 
workers; and (5) factors that impede adequate pulmonary toilet, such as 
surgical procedures involving the head, neck, thorax, or upper abdomen, 
and immobilization due to trauma or illness.7,\\33-
35,\\59,\\128

A. Oropharyngeal, Tracheal, and Gastric Colonization

    The association between colonization of the 
oropharynx,81,\\130 trachea,131 or 
stomach103,\\104,\\110,\\116 and predisposition to 
gram-negative bacillary pneumonia prompted attempts to prevent 
infection either by prophylactic local application of antimicrobial 
agent(s)132,\\133 or utilizing the phenomenon of local 
bacterial interference.134,\\135 Although early work 
suggested that the former method, aerosolized antimicrobials, could 
eradicate common gram-negative pathogens from the upper respiratory 
tract,131 superinfection occurred in some patients receiving this 
therapy.132-134,\\136,\\137 The latter method, bacterial 
interference (with alpha-hemolytic streptococci), has been successfully 
used by some investigators to prevent oropharyngeal colonization by 
aerobic gram-negative bacilli.134 However, the efficacy of this 
method for use in general has not been evaluated.
    The administration of antacids and H2-blockers for prevention of 
stress bleeding in critically ill, postoperative, and/or mechanically 
ventilated patients has been associated with gastric bacterial 
overgrowth in many 
studies.34,\\105,\\106,\\111,\\115,\\116,\
\138-140 Sucralfate, a cytoprotective agent that has little effect 
on gastric pH and may have bactericidal properties of its own, has been 
suggested as a potential substitute for antacids and H2-
blockers.141-143 The results of clinical trials comparing the risk 
of pneumonia in patients receiving sucralfate to that in patients given 
antacids and/or H2-blockers have been 
variable.105,\\111,\\140,\\141,\\144,\\145
 In most randomized trials, ICU patients receiving mechanically 
assisted ventilation and antacids with or without H2-b lockers had 
increased gastric pH, high bacterial counts in the gastric fluid, and 
increased risk of pneumonia compared with patients given 
sucralfate.105,\\111,\\140,\\141,\\144 In one 
report with a large number of study patients, the incidence of early-
onset pneumonia (occurring 4 days after intubation) did not 
differ between patient groups, but late-onset pneumonia occurred in 5% 
of 76 patients who received sucralfate, 16% of 69 given antacids, and 
21% of 68 who received an H2-blocker.140 On the other hand, a 
meta-analysis of data from eight earlier studies did not show a strong 
association between nosocomial pneumonia and drugs that raise gastric 
pH.146 Further comparative studies are underway in which 
bronchoscopy with PSB or BAL is utilized for the diagnosis of 
pneumonia.
    Selective decontamination of the digestive tract (SDD) is another 
strategy designed to prevent bacterial colonization and lower 
respiratory tract infection in mechanically ventilated 
patients.147-170 SDD is aimed at preventing oropharyngeal and 
gastric colonization with aerobic gram-negative bacilli and Candida 
spp., without altering the anaerobic flora (Table 2).147-170 A 
variety of SDD regimens use a combination of locally administered 
nonabsorbable antibiotic agents such as polymyxin, an aminoglycoside 
(tobramycin, gentamicin, or, rarely, neomycin), or a quinolone 
(norfloxacin or ciprofloxacin), coupled with either amphotericin B or 
nystatin. The local antimicrobial preparation is applied as a paste to 
the oropharynx and given orally or via the nasogastric tube four times 
a day. In addition, in many studies, a systemic (intravenous) 
antimicrobial such as cefotaxime or trimethoprim is administered to the 
patient.
    While most clinical trials,147-151,\\153-
160,\\162,\\164,\\169 including two meta-
analyses,163,\\170 of SDD have demonstrated a decrease in the 
rates of nosocomial respiratory infections, these trials have been 
difficult to assess because they have differed in study design and 
population, and many have had short follow-up periods (Table 2). In 
most of these studies, the diagnosis of pneumonia was based on clinical 
criteria; bronchoscopy with BAL or PSB was used in only a few 
studies.152,\\153,\\164,\\167,\\169
    Two recently published large double-blind, placebo-controlled 
trials demonstrated no benefit from SDD.166,\\167 In one, a 
large French multicenter study by Gastinne et al, a significant 
decrease in incidence of gram-negative bacillary pneumonia was not 
accompanied by a decrease in pneumonia from all causes.167 In the 
other study, by Hammond et al, no differences were noted between 
patients randomized to SDD or to placebo; however, both patient groups 
received intravenous cefotaxime.166
    Although an earlier meta-analysis suggested a trend toward 
decreased mortality in patients given SDD,163 a more recent and 
more extensive analysis highlights the equivocal effect of SDD on 
patient mortality, as well as the high cost of using SDD to prevent 
pneumonia or death (i.e., in order to prevent one case of nosocomial 
pneumonia, or one death due to nosocomial pneumonia, 6 [range: 5-9] or 
23 [range: 13-39] patients, respectively, would have to be given 
SDD.170 Furthermore, there are concerns over the development of 
antimicrobial resistance and superinfection with gram-positive bacteria 
and other antibiotic-resistant nosocomial 
pathogens.148,\\149,\\152,\\155 Thus, currently 
available data do not justify the routine use of SDD for prevention of 
nosocomial pneumonia in ICU patients. SDD may be ultimately useful for 
specific subsets of ICU patients, such as those with trauma or severe 
immunosuppression, e.g., bone-marrow transplant recipients.
    A new approach advocated to prevent oropharyngeal colonization in 
patients receiving enteral nutrition is to reduce bacterial 
colonization of the stomach by acidifying the enteral feed.171 
Although the absence of bacteria from the stomach has been confirmed in 
patients given acidified enteral feeding, the effect on the incidence 
of nosocomial pneumonia has not been evaluated.171

B. Aspiration of Oropharyngeal and Gastric Flora

    Clinically significant aspiration usually occurs in patients who 
have one or more of the following conditions: a depressed level of 
consciousness, dysphagia due to neurologic or esophageal disorders, an 
endotracheal (naso- or oro-tracheal) and nasogastric tube in place, and 
receipt of enteral feeding.35,\\79,\\80,\\172-176 
Placement of nasogastric tube may increase nasopharyngeal colonization, 
cause reflux of gastric contents, or allow bacterial migration via the 
tube from the stomach to the upper airway.173,\\176-178 When 
enteral feedings are administered, gross contamination of the enteral 
solution during preparation179-181 and elevated gastric 
pH67,\\182,\\183 may lead to gastric colonization with 
gram-negative bacilli. In addition, gastric reflux and aspiration may 
occur because of increased intragastric volume and 
pressure.67,\\110,\\173
    Prevention of pneumonia in such patients may be difficult, but 
methods that make regurgitation less likely, for example, placing the 
patient in a semirecumbent position by elevating the head of the 
bed,175,\\184,\\185 administering enteral nutrition 
intermittently in small boluses rather than 
continuously,67,\\183 using flexible, small-bore enteral 
tubes,176,\\186 and witholding enteral feeding when the 
residual volume in the stomach is large or if bowel sounds are not 
heard upon auscultation of the abdomen, may be 
beneficial.175,\\187,\\188 On the other hand, placing 
the enteral tube below the stomach (e.g. in the jejunum) has yielded 
equivocal results.189,\\190

C. Mechanically Assisted Ventilation and Endotracheal Intubation

    Patients receiving continuous, mechanically assisted ventilation 
have 6-21 times the risk of developing nosocomial pneumonia compared 
with patients not receiving ventilatory 
support.34,\\60,\\62,\\70 Data from the study by 
Fagon and co-workers indicate that the risk of developing ventilator-
associated pneumonia increases by 1% per day.6 This increased risk 
is partly due to carriage of oropharyngeal organisms upon passage of 
the endotracheal tube into the trachea during intubation, as well as to 
depressed host defenses secondary to the patient's severe underlying 
illness.7,\\34,\\35,\\191 In addition, bacteria can 
aggregate on the surface of the tube over time and form a glycocalyx 
(biofilm) that protects the bacteria from action of antimicrobial 
agents or host defenses.192 Some investigators believe that these 
bacterial aggregates may become dislodged by ventilation flow, tube 
manipulation, or suctioning, and subsequently embolize into the lower 
respiratory tract and cause focal pneumonia.193,\\194 
Removing tracheal secretions by gentle suctioning and using aseptic 
technique to reduce cross-contamination from respiratory therapy 
equipment or hands of personnel have been utilized traditionally to 
help prevent pneumonia in patients receiving mechanically assisted 
ventilation.
    The risk of pneumonia is also increased by the direct access of 
bacteria to the lower respiratory tract, often because of leakage 
around the endotracheal cuff,195,\\196 which allows pooled 
secretions above the cuff to enter the trachea.197 In one recent 
study, the occurrence of nosocomial pneumonia was delayed and decreased 
in intubated patients whose endotracheal tubes had a separate dorsal 
lumen that allowed drainage (by suctioning) of secretions in the space 
above endotracheal cuff and below the glottis.197 However, further 
studies are needed to determine the cost-benefit ratio of using this 
device.

D. Cross-Colonization Via Hands of Personnel

    Pathogens causing nosocomial pneumonia, such as gram-negative 
bacilli and Staphylococcus aureus, are ubiquitous in the hospital, 
especially in intensive or critical care areas.198,\\199 
Transmission of these microorganisms to patients frequently occurs via 
healthcare workers' hands that become contaminated or transiently 
colonized with the microorganisms.200-205 Procedures such as 
tracheal suctioning and manipulation of ventilator circuit or 
endotracheal tubes increase the opportunity for cross-contamination. 
The risk of cross-contamination can be reduced by using aseptic 
technique and sterile or disinfected equipment when appropriate62 
and eliminating pathogens from the hands of 
personnel.62,\\206-208
    In theory, adequate handwashing is an effective way of removing 
transient bacteria from the hands,207,\\208 but personnel 
compliance with handwashing has been generally poor, despite the best 
efforts at educating healthcare workers.209-212 For this reason, 
the routine use of gloves has been advocated to help prevent cross-
contamination.213,\\214 Routine gloving (in addition to 
gowning) was associated with a decrease in the incidence of nosocomial 
respiratory-syncytial virus (RSV)215 and other ICU 
infections.216 It should be emphasized, however, that nosocomial 
pathogens can colonize gloves,217 and that outbreaks have been 
traced to healthcare workers who did not change gloves after patient 
contact.218

E. Contamination of Devices Used on the Respiratory Tract

    Devices used on the respiratory tract for respiratory therapy 
(e.g., nebulizer), diagnostic examination (e.g., bronchoscope or 
spirometer), and administration of anesthesia are potential reservoirs 
or vehicles for infectious microorganisms.62,\\219-221 Routes 
of transmission may be from device to 
patient,120,\\122,\\221-230 from one patient to another, 
or from one body site to the lower respiratory tract of the same 
patient via hand or device.220,\\231,\\232 Contaminated 
nebulizer reservoirs can allow the growth of hydrophilic bacteria that 
may be subsequently aerosolized during device 
use.119,\\122,\\123,\\228 Gram-negative bacilli 
such as Pseudomonas spp., Xanthomonas spp., Flavobacterium spp., 
Legionella spp., and nontuberculous mycobacteria can multiply to 
substantial concentrations in nebulizer fluid227,\\233-235 
and increase the patient's risk of acquiring pneumonia.120-
123,\\227,\\228,\\236,\\237
    Proper cleaning and sterilization or disinfection of reusable 
equipment are important components of a program to reduce infections 
associated with respiratory therapy and anesthesia equipment.221-
226,238,239 Respiratory therapy devices have been classified as semi-
critical because they come into contact with mucous membranes but do 
not ordinarily penetrate body surfaces, and the associated infection 
risk following their use in patients is less than that associated with 
devices that penetrate normally sterile tissues (See Appendix 
A).240 There is no evidence that low-level contamination of 
respiratory therapy device prior to use by a patient, as may occur 
following high-level disinfection of the device, presents a greater 
risk of respiratory infection than does sterile equipment. Thus, if 
after they are thoroughly cleaned, these devices cannot be sterilized 
by steam autoclave or ethylene oxide,241 they can be subjected to 
high-level disinfection by pasteurization at 75 deg.C for 30 
min,242-244 or by using liquid chemical disinfectants approved by 
the Environmental Protection Agency (EPA) as sterilants/
disinfectants.214,245-247 When rinsing is needed after a 
respiratory device has been sterilized or disinfected, only sterile 
water is used because tap or locally-prepared distilled water may 
harbor microorganisms that can cause pneumonia.233,234,248-250
1. Mechanical Ventilators and Anesthesia Machines
    The internal machinery of mechanical ventilators and anesthesia 
machines is not considered an important source of bacterial 
contamination of inhaled air.251 Thus, routine sterilization or 
high-level disinfection of the internal machinery is considered 
unnecessary. Using high-efficiency bacterial filters at various 
positions in the breathing circuit had been advocated 
previously.252,253 Filters interposed between the machinery and 
the main breathing circuit can eliminate contaminants from the driving 
gas and prevent retrograde contamination of the machine by the patient 
but may also alter the functional specifications of the breathing 
device by impeding high gas flows.252,253 In addition, when used 
with anesthesia equipment, filters placed between the inspiratory-phase 
circuit and the patient have not been shown to prevent 
infections.254,255 Placement of a filter or condensate trap at the 
expiratory-phase tubing of the mechanical-ventilator circuit may help 
prevent cross-contamination of the ventilated patient's immediate 
environment,231,256 but the importance of such filters in 
preventing nosocomial pneumonia needs further evaluation.
2. Humidifiers, Breathing Circuits, and Heat-Moisture Exchangers
    Most U.S. hospitals currently use ventilators with either bubble-
through or wick humidifiers that produce either 
insignificant125,257 or no aerosols, respectively, for 
humidification. Thus, they do not seem to pose an important risk for 
pneumonia in patients. In addition, bubble-through humidifiers are 
usually heated to temperatures that reduce or eliminate bacterial 
pathogens.257,258 Sterile water, however, is still generally used 
to fill these humidifiers259 because tap or distilled water may 
harbor Legionella spp. that are more heat-resistant than other 
bacteria.236,250
    The potential risk for pneumonia in patients using mechanical 
ventilators with heated bubble-through humidifiers stems primarily from 
the condensate that forms in the inspiratory-phase tubing of the 
ventilator circuit as a result of the difference in the temperatures of 
the inspiratory-phase gas and ambient air; condensate formation 
increases if the tubing is unheated.260 The tubing and condensate 
can rapidly become contaminated, usually with bacteria that originate 
from the patient's oropharynx.260 In the study by Craven et al, 
33% of inspiratory circuits were colonized with bacteria from patients' 
oropharynx within 2 hours and 80% within 24 hours of use.260 
Spillage of the contaminated condensate into the patient's 
tracheobronchial tree, as can occur during procedures in which the 
tubing may be moved (e.g., suctioning, adjusting the ventilator 
setting, or feeding or caring for the patient), may increase the risk 
of pneumonia in the patient.260 Thus, in many hospitals, 
healthcare workers are trained to prevent such spillage and to drain 
the fluid periodically. Microorganisms contaminating ventilator-circuit 
condensate can be transmitted to other patients via hands of the 
healthcare worker handling the fluid, especially if the healthcare 
worker fails to wash his or her hands after handling the condensate.
    The role of ventilator-tubing changes in preventing pneumonia in 
patients using mechanical ventilators with bubble-through humidifiers 
has been investigated. Initial studies of in-use contamination of 
mechanical ventilator circuits with humidifiers have shown that neither 
the rate of bacterial contamination of inspiratory-phase gas nor the 
incidence of pneumonia was significantly increased when tubings were 
changed every 24 hours rather than every 8 or 16 hours.261 Craven 
et al later showed that changing the ventilator circuit every 48 hours 
rather than 24 hours did not result in an increase in contamination of 
the inspiratory-phase gas or tubing of the ventilator circuits.\262\ In 
addition, the incidence of nosocomial pneumonia was not significantly 
higher when circuits were changed every 48 hours than when changes were 
done every 24 hours.\262\ More recent reports suggest that the risk of 
pneumonia may not increase when the interval for circuit change is 
prolonged beyond 48 hours. Dreyfuss and others showed that the risk of 
pneumonia (8 [29%] of 28) was not significantly higher when the 
circuits were never changed for the duration of use by the patient, 
than (11 [31%] of 35) when the circuits were changed every 48 
hours.\263\
    These findings indicate that the recommended daily change in 
ventilator circuits may be extended to 48 hours. This change 
in recommendation is expected to result in large savings in device use 
and personnel time for U.S. hospitals.259,262 The maximum time, 
however, that a circuit can be safely left unchanged on a patient has 
yet to be determined.
    Condensate formation in the inspiratory-phase tubing of a 
ventilator breathing circuit can be decreased by elevating the 
temperature of the inspiratory-phase gas with a heated wire in the 
inspiratory-phase tubing. However, in one report, three cases of 
endotracheal- or tracheostomy-tube blockage by dried-up patient 
secretions were attributed to the decrease in the relative humidity of 
inspired gas that results from the elevation of the gas 
temperature.\264\ Until further data are available about the frequency 
of the occurrence of such cases, users of heated ventilator tubing 
should be aware of the advantages and potential complications of using 
heated tubing.
    Condensate formation can be eliminated by using a heat-moisture 
exchanger (HME) or a hygroscopic condenser humidifier (``artificial 
nose'').265,270 An HME recycles heat and moisture exhaled by the 
patient, and eliminates the need for a humidifier. In the absence of a 
humidifier, no condensate forms in the inspiratory-phase tubing of the 
ventilator circuit. Thus, bacterial colonization of the tubing is 
prevented, and the need to routinely change tubings periodically is 
obviated. Some models of HMEs are equipped with bacterial filters, but 
the advantage of these filters remains unknown. HMEs can increase the 
dead space and resistance to breathing, may leak around the 
endotracheal tube, and may result in drying of sputum and blockage of 
the tracheo-bronchial tree.271 Although recently developed HMEs 
with humidifiers increase airway humidity without increasing 
colonization with bacteria,267,272 more studies are needed to 
determine whether the incidence of pneumonia is decreased.273-276
3. Large-Volume Nebulizers
    Nebulizers with large-volume (>500 cc) reservoirs, including those 
used in intermittent positive-pressure breathing (IPPB) machines and 
ultrasonic or spinning-disk room-air ``humidifiers,'' pose the greatest 
risk of pneumonia to patients, probably because of the total amount of 
aerosol they generate.222,225,227,236,277 These reservoirs can 
become contaminated by hands of personnel, unsterile humidification 
fluid, or inadequate sterilization or disinfection between uses.\119\ 
Once introduced into the reservoir, various bacteria, including 
Legionella spp., can multiply to sufficiently large numbers within 24 
hours to pose a risk of infection in patients who receive inhalation 
therapy.121,122,227,237,277 Sterilization or high-level 
disinfection of these nebulizers can eliminate vegetative bacteria from 
their reservoirs and make them safe for patient use.\240\ Unlike 
nebulizers attached to IPPB machines, however, room-air ``humidifiers'' 
have a high cost-benefit ratio: evidence of clinical benefits from 
their use in hospitals is lacking, and the potential cost of daily 
sterilization or disinfection of, and use of sterile water to fill, 
such devices is substantial.
4. Small-Volume Medication Nebulizers
    Small-volume medication nebulizers for administration of 
bronchodilators, including those that are hand-held and those that are 
in the inspiratory circuit of mechanical ventilators, can produce 
bacterial aerosols.\228\ Hand-held nebulizers have rarely been 
associated with nosocomial pneumonia, and only when contaminated by 
medications from multidose vials.\278\ Medication nebulizers inserted 
in the ventilator circuit (``in-line'') may become contaminated by 
condensate in the inspiratory tubing and increase the patient's risk of 
pneumonia because the nebulizer aerosol is directed through the 
endotracheal tube and bypasses many of the normal host defenses against 
infection.\260\
5. Suction Catheters, Resuscitation Bags, Oxygen Analyzers, and 
Ventilator Spirometers
    Tracheal suction catheters can introduce microorganisms into a 
patient's lower respiratory tract. Preliminary studies suggest that the 
risk of pneumonia is not different between patients on whom the single-
use suction method is used and those on whom the newly developed closed 
multi-use catheter system is used.\279\ In addition, the advantages of 
using one system over the other, in terms of oxygen desaturation in 
patients and less environmental contamination, have not been clearly 
shown.280-282
    Resuscitation bags are particularly difficult to clean and dry 
between uses; microorganisms in secretions or fluid left in the bag may 
be aerosolized and/or sprayed into the lower respiratory tract of the 
patient on whom the bag is used; in addition, contaminating 
microorganisms may be transmitted from one patient to another via hands 
of staff members.283-285 Oxygen analyzers and ventilator 
spirometers have been associated with outbreaks of gram-negative 
respiratory tract colonization and pneumonia resulting from patient-to-
patient transmission of organisms via hands of personnel.220,286 
These devices require sterilization or high-level disinfection between 
uses on different patients. Education of physicians, respiratory 
therapists, and nursing staff regarding the associated risks and 
appropriate care of these devices is essential.

F. Thoraco-Abdominal Surgical Procedures

    Certain patients are at high risk of developing postoperative 
pulmonary complications, including pneumonia. These persons include 
those who are more than 70 years of age, are obese, or have chronic 
obstructive pulmonary disease.287-290 Abnormal pulmonary function 
tests (especially decreased maximum expiration flow rate), a history of 
smoking, the presence of tracheostomy or prolonged intubation, or 
protein depletion that can cause respiratory-muscle weakness are also 
risk factors.59,65,129 Patients who undergo surgery of the head, 
neck, thorax, or abdomen may suffer from impairment of normal 
swallowing and respiratory clearance mechanisms as a result of 
instrumentation of the respiratory tract, anesthesia, or increased use 
of narcotics and sedatives;288,291,292 patients who undergo upper 
abdominal surgery usually suffer from diaphragmatic dysfunction that 
results in decreased functional residual capacity of the lungs, closure 
of airways, and atelectasis.293,294 Interventions aimed at 
reducing the postoperative patient's risk of pneumonia have been 
developed.\295\ These include deep breathing exercises, chest 
physiotherapy, use of incentive spirometry, IPPB, and continuous 
positive airway pressure (CPAP) by face mask.295-305 Studies 
evaluating the relative efficacy of these modalities have shown 
variable results, and have been difficult to compare because of 
differences in outcome variables assessed, patient populations studied, 
and study design.295,297,298,304-307 Nevertheless, many studies 
have found deep breathing exercises, chest physiotherapy, use of 
incentive spirometry, and IPPB as advantageous maneuvers, especially in 
patients with preoperative pulmonary 
dysfunction.298,299,301,302,304-306 In addition, control of pain 
that interferes with cough and deep breathing during the immediate 
postoperative period has been shown to decrease the incidence of 
pulmonary complications after surgery; several methods of controlling 
pain have been used; these include intramuscular or intravenous 
(including patient-controlled) administration, or regional (e.g., 
epidural) analgesia.308-315

G. Other Prophylactic Measures

1. Vaccination of Patients
    Although pneumococci are not a major cause of nosocomial pneumonia, 
they have been identified as etiologic agents of serious nosocomial 
pulmonary infection and bacteremia.316-318 The following factors 
render patients at high risk of complications from pneumococcal 
infections: 65 years of age, chronic cardiovascular or 
pulmonary disease, diabetes mellitus, alcoholism, cirrhosis, 
cerebrospinal fluid leaks, immunosuppression, functional or anatomic 
asplenia, or HIV infection. Pneumococcal vaccine is effective in 
preventing pneumococcal disease.319,320 Because two-thirds or more 
of patients with serious pneumococcal disease have been hospitalized at 
least once within 5 years before their pneumococcal illness, offering 
pneumococcal vaccine in hospitals, e.g., at the time of patient 
discharge, should contribute substantially to preventing the 
disease.319,321
2. Prophylaxis With Systemic Antimicrobial Agents
    Systemic antimicrobial administration has been a prevalent practice 
in the prevention of nosocomial infections, including pneumonia, 
especially in patients who are weaned off mechanical ventilators, 
postoperative, and/or critically ill.322 However, the efficacy of 
such practice is questionable; and the potential for superinfection, 
which may result from any antimicrobial therapy, is a 
problem.84,322-326
3. Kinetic Therapy for the Immobilized State
    Continuous lateral rotational therapy (CLRT) or ``kinetic'' therapy 
is a recently introduced maneuver for prevention of pulmonary and other 
complications from prolonged immobilization or bed rest, such as in 
patients with acute stroke, critical illness, head injury or traction, 
blunt chest trauma, and/or mechanically assisted ventilation.327-
332 CLRT involves the use of a bed that turns continuously and slowly 
(about eight full rotations per hour) along its longitudinal axis. 
Among the hypothesized benefits of CLRT are improved drainage of 
secretions within the lungs and lower airways, increased tidal volume, 
and reduction of venous thrombosis with resultant pulmonary 
embolization.174,333-335 However, the efficacy of CLRT in 
preventing pneumonia needs further evaluation because available studies 
yielded variable results.327-330 In addition, the studies either 
involved small numbers of patients,328 lacked adequate 
randomization,327 had no clear definition of pneumonia,327 
did not distinguish between community-acquired and nosocomial 
pneumonia,328,332 or did not adjust for possible confounding 
factors such as mechanical ventilation, endotracheal intubation, 
nasogastric intubation, and enteral feeding.327

LEGIONNAIRES' DISEASE

    Legionnaires' disease is a multisystem illness, with pneumonia, 
caused by Legionella spp. In contrast, Pontiac fever is a self-limited 
influenza-like illness, without pneumonia, that is associated with 
Legionella spp.336

I. Epidemiology

    Since identification of the etiologic agent, numerous outbreaks of 
nosocomial Legionnaires' disease have been reported and have provided 
the opportunity to study the epidemiology of epidemic legionellosis. In 
contrast, the epidemiology of endemic Legionnaires' disease has not 
been well elucidated. The overall proportion of nosocomial pneumonias 
due to Legionella spp. in North America has not been determined, 
although individual hospitals have reported a ranges of 0%-
14%.337-339 Because diagnostic tests for Legionella spp. infection 
are not routinely performed on all patients with hospital-acquired 
pneumonia in most hospitals, this range probably underestimates the 
incidence of Legionnaires' disease.
    Legionella spp. are commonly found in a variety of natural and man-
made aquatic environments340,341 and may enter hospital water 
systems in low or undetectable numbers.342,343 Cooling towers, 
evaporative condensers, heated potable-water-distribution systems 
within hospitals, and locally produced distilled water can provide a 
suitable environment for legionellae to multiply. Factors known to 
enhance colonization and amplification of legionellae in man-made water 
environments include temperatures of 25-42 deg.C,344-349 
stagnation,350 scale and sediment,346 and the presence of 
certain free-living aquatic amoebae that are capable of supporting 
intracellular growth of legionellae.351,352
    A person's risk of acquiring legionellosis following exposure to 
contaminated water depends on a number of factors, including the type 
and intensity of exposure and the exposed person's health 
status.353-355 Persons with severe immunosuppression or chronic 
underlying illnesses, such as hematologic malignancy or end-stage renal 
disease, are at markedly increased risk for legionellosis.355-358 
Persons in the later stages of acquired immunodeficiency syndrome are 
also probably at increased risk of legionellosis, but data are limited 
because of infrequent testing of patients. Persons with diabetes 
mellitus, chronic lung disease, or non-hematologic malignancy, those 
who smoke cigarettes, and the elderly are at moderately increased 
risk.336 Nosocomial Legionnaires' disease has also been reported 
among patients at children's hospitals.359,360
    Underlying disease and advanced age are not only risk factors for 
acquiring Legionnaires' disease but also for dying from the illness. In 
a multivariate analysis of 3,524 cases reported to CDC from 1980 
through 1989, immunosuppression, advanced age, end-stage renal disease, 
cancer, and nosocomial acquisition of disease were each independently 
associated with a fatal outcome.355 The mortality rate among 803 
persons with nosocomially acquired cases was 40% compared with 20% 
among 2,721 persons with community-acquired cases,355 probably 
reflecting increased severity of underlying disease in hospitalized 
patients.

II. Diagnosis

    The clinical spectrum of disease due to Legionella spp. is broad 
and ranges from asymptomatic infection to rapidly progressive 
pneumonia. Legionnaires' disease cannot be distinguished clinically or 
radiographically from pneumonia caused by other agents,\361\,\362\ and 
evidence of infection with other respiratory pathogens does not rule 
out the possibility of concomitant Legionella spp. infection.363-
365
    The diagnosis of legionellosis may be confirmed by any one of the 
following: Culture isolation of Legionella from respiratory secretions 
or tissues, or microscopic visualization of the bacterium in 
respiratory secretions or tissue by immunofluorescent microscopy; and, 
for legionellosis due to L. pneumophila serogroup 1, detection of L. 
pneumophila serogroup-1 antigens in urine by radioimmunoassay, or 
observation of a four-fold rise in L. pneumophila serogroup-1 antibody 
titer to 1:128 in paired acute and convalescent serum 
specimens by use of an indirect immunofluorescent antibody test 
(IFA).\366\ A single elevated antibody titer does not confirm a case of 
Legionnaires' disease because IFA titers 1:256 are found in 
1-16% of healthy adults.364,367-370
    Because the above tests complement each other, performing each test 
when Legionnaires' disease is suspected increases the probability of 
confirming the diagnosis.\371\ However, because none of the laboratory 
tests is 100% sensitive, the diagnosis of legionellosis is not ruled 
out even if one or more of the tests are negative.371,372 Of the 
available tests, the most specific is culture isolation of Legionella 
sp. from any respiratory tract specimen.373,374

III. Modes of Transmission

    Inhalation of aerosols of water contaminated with Legionella sp. is 
believed to be the primary mechanism of entry of these organisms into a 
patient's respiratory tract.\336\ In several hospital outbreaks, 
patients were considered to be infected through exposure to 
contaminated aerosols generated by cooling towers, showers, faucets, 
respiratory therapy equipment, and room-air humidifiers.227,375-
382 In several studies, aspiration of contaminated potable water has 
been proposed as the mode of transmission to certain patients.383-
385 Person-to-person transmission, however, has not been observed.

IV. Definition of Nosocomial Legionnaires' Disease

    The incubation period for Legionnaires' disease is generally 2-10 
days; thus, for epidemiologic purposes, in this document and in the 
accompanying recommendations by the HICPAC, laboratory-confirmed 
legionellosis that occurs in a patient who has spent 10 days 
continuously in the hospital prior to onset of illness is considered 
definite nosocomial Legionnaires' disease, and laboratory-confirmed 
infection that occurs 2-10 days after hospitalization is possible 
nosocomial infection.

V. Prevention and Control Measures

A. Prevention of Legionnaires' Disease in Hospitals With No Identified 
Cases (Primary Prevention)

    Prevention strategies in healthcare facilities with no cases of 
nosocomial legionellosis have varied by institution, depending on the 
immunologic status of the patients, the design and construction of the 
facility, resources available for implementation of prevention 
strategies, and state and local regulations.
    There are at least two schools of thought regarding the most 
appropriate and cost-effective approach to prevent nosocomial 
legionellosis, especially in hospitals where no cases or only sporadic 
cases of the illness are detected. However, a study comparing the cost-
benefit ratios of these strategies has not been done.
    The first approach is based on periodic, routine culturing of water 
samples from the hospital's potable water system, for Legionella 
spp.387 When a positive culture is obtained, the hospital's 
potable water system is decontaminated and diagnostic laboratory tests 
for legionellosis are made available to clinicians in the hospital's 
microbiology department, so that active surveillance for cases can be 
instituted.388 This approach is based on the premise that no cases 
of nosocomial legionellosis can occur in the absence of Legionella spp. 
from the potable water system, and, conversely, once Legionella spp. 
are cultured from the water, cases of nosocomial legionellosis may 
occur.383,389 Proponents of this strategy indicate that when 
physicians are informed that the potable water system of the hospital 
is culture-positive for Legionella spp., they are more inclined to 
conduct the necessary tests for legionellosis.388 A potential 
advantage of this approach is the lower cost of culturing a limited 
number of water samples, if the testing is done infrequently, compared 
with the cost of routine laboratory diagnostic testing for 
legionellosis in all patients with nosocomial pneumonia in hospitals 
that have had no cases of nosocomial legionellosis.
    The main argument against this approach is that in the absence of 
cases, the relationship between the results of water cultures and the 
risk of legionellosis remains undefined. The bacterium has been 
frequently present in hospital water systems,390 often without 
being associated with known cases of disease.250,338,391,392 In a 
study of 84 hospitals in Quebec, 68% were found to be colonized with 
Legionella spp., and 26% were colonized at >30% of sites sampled; 
however, cases of Legionnaires' disease were rarely reported from these 
hospitals.250 Similarly, at one hospital where active surveillance 
for legionellosis and environmental culturing for Legionella spp. were 
done, no cases of legionellosis occurred in a urology ward during a 
3.5-month period when 70% of water samples from the ward were culture-
positive for L. pneumophila serogroup 1.338 Interpretation of the 
results of routine culturing of water may be confounded by variable 
culture results among sites sampled within a single water system and by 
fluctuations in the concentration of Legionella spp. in the same 
site.393,394 In addition, the risk of illness following exposure 
to a given source may be influenced by a number of factors other than 
the presence or concentration of organisms; these include the degree to 
which contaminated water is aerosolized into respirable droplets, the 
proximity of the infectious aerosol to potential host, the 
susceptibility of the host, and the virulence properties of the 
contaminating strain.395-397 Thus, data are insufficient to assign 
a level of risk of disease even on the basis of the number of colony-
forming units detected in samples from the hospital environment. By 
routinely culturing water samples, many hospitals will have to be 
committed to water-decontamination programs to eradicate Legionella 
spp. Because of this problem, routine monitoring of water from the 
hospital's potable water system and from aerosol-producing devices is 
not widely recommended.398
    The second approach to prevent and control nosocomial legionellosis 
is by: (a) Maintaining a high index of suspicion for legionellosis and 
appropriately using diagnostic tests for legionellosis in patients with 
nosocomial pneumonia who are at high risk of developing the disease and 
dying from the infection,338,399 (b) initiating an investigation 
for a hospital source of Legionella spp. upon identification of one 
laboratory-confirmed case of definite or two laboratory-confirmed cases 
of possible nosocomial Legionnaires' disease, and (c) routinely 
maintaining cooling towers and using only sterile water for filling and 
terminal rinsing of nebulization devices.
    In hospitals with no identified cases of legionellosis, further 
study is needed of the cost-benefit ratio of control measures aimed at 
creating an environment that is not conducive to survival or 
multiplication of Legionella spp., e.g., routine maintenance of potable 
water at 50 deg.C or <20 deg.C at the tap or chlorination of 
heated water to achieve 1-2 mg/L free residual chlorine at the 
tap.338,383,393,400-403

B. Prevention of Legionnaires' Disease in Hospitals With Identified 
Cases (Secondary Prevention)

    The indications for a full-scale environmental investigation to 
search for and subsequently decontaminate identified sources of 
Legionella spp. in hospital environments remain to be elucidated, and 
probably vary from hospital to hospital. In institutions where as few 
as 1-3 nosocomial cases are identified over a period of up to several 
months, intensified surveillance for Legionnaires' disease has 
frequently detected numerous additional cases.357,376,380,401 This 
suggests the need for a low threshold for initiating an investigation 
following the identification of nosocomial, laboratory-confirmed cases 
of legionellosis. However, when developing a strategy to respond to 
such an identification, infection-control personnel should consider the 
level of risk of nosocomial acquisition of, and mortality from, 
Legionella spp. infection at their particular hospital.
    An epidemiologic investigation of the source of Legionella spp. 
involves several important steps, including retrospective review of 
microbiologic and medical records, active surveillance to identify all 
recent or ongoing cases of legionellosis, identification of risk 
factors (including environmental exposures for infection, such as 
showering or use of respiratory-therapy equipment), collection of water 
samples from environmental sources implicated by the epidemiologic 
investigation and from other potential sources of aerosolized water, 
and subtype-matching between legionellae isolated from patients and 
environmental samples.382,404-406 The latter step can be crucial 
in supporting epidemiologic evidence of a link between human illness 
and a specific source.407
    In hospitals where the heated-water system has been identified as 
the source of the organism, the system has been decontaminated by pulse 
(one-time) thermal disinfection or superheating (i.e., flushing for at 
least 5 minutes each distal outlet of the hot-water system with water 
at 65 deg.C) and hyperchlorination (flushing all outlets of 
the hot-water system with water containing 10 mg/L free 
residual chlorine).403,408-410 Following either of these 
procedures, most hospitals maintain heated-water at 50 deg.C 
or <20 deg.C at the tap or chlorinate heated water to achieve 1-2 mg/L 
free residual chlorine at the tap.338,383,393,400-403 Additional 
measures, such as physical cleaning or replacement of hot-water storage 
tanks, water-heaters, faucets, and showerheads, may be required because 
scale and sediment that provide organisms protection from the biocidal 
effects of heat and chlorine, may accumulate in them.346,403 
Alternative methods for control and eradication of legionellae in water 
systems, such as treatment of water with ozone, ultraviolet light, or 
heavy metal ions, have limited the growth of legionellae under 
laboratory,344,411,412 or, in the case of ultraviolet light, 
operating conditions.413 However, further data are needed 
regarding the efficacy of these methods when used in hospital water 
systems414 before they can be considered standard. In hospitals 
where the cooling towers are contaminated, measures for decontamination 
have been previously published.415
    For highly immunocompromised patients, other preventive measures 
have been used. At one hospital, immunosuppressed patients were 
restricted from taking showers, and, for these patients, only sterile 
water was used for drinking or flushing nasogastric tubes;384 In 
another hospital, a combined approach, consisting of continuous 
heating, particulate filtration, ultraviolet treatment, and monthly 
pulse hyperchlorination of the water supply of the bone-marrow 
transplant unit, was used to decrease the incidence of Legionnaires' 
disease.413
    In view of the high cost of an environmental investigation and of 
instituting control measures to eradicate Legionella spp. from sources 
in the hospital416,417 and the differential risk, based on host 
factors, for acquiring nosocomial legionellosis and of having severe 
and fatal infection with the microorganism, the decision to search for 
and the choice of procedures to eradicate hospital environmental 
sources of Legionella spp. should take into account the type of patient 
population served by the hospital.

ASPERGILLOSIS

I. Epidemiology

    Aspergillus spp. are ubiquitous fungi, commonly occurring in soil, 
water, and decaying vegetation. Aspergillus spp. have been cultured 
from unfiltered air, ventilation systems, contaminated dust dislodged 
during hospital renovation and construction, horizontal surfaces, food, 
and ornamental plants.418
    A. fumigatus and A. flavus are the most frequently isolated 
Aspergillus spp. in patients with proven aspergillosis.419 
Nosocomial aspergillosis has been recognized increasingly as a cause of 
severe illness and mortality in highly immunocompromised patients, 
e.g., patients undergoing chemotherapy and/or organ transplantation, 
including bone-marrow transplantation for hematologic and other 
malignant neoplasms.420-423
    The most important nosocomial infection due to Aspergillus spp. is 
pneumonia.424 Hospital outbreaks of pulmonary aspergillosis have 
occurred mainly in granulocytopenic patients, especially in bone-marrow 
transplant units.424-430 Although invasive aspergillosis has been 
reported in recipients of solid-organ transplants (e.g., heart or 
kidney),431-435 the incidence of Aspergillus spp. infections in 
these patients has been lower than in recipients of bone-marrow 
transplants, probably because of the recent decrease in the use of 
corticosteroids and the introduction of cyclosporine.433,436 In 
solid-organ transplant recipients, the efficacy of infection control 
measures, such as provision of protected environments and prophylaxis 
with antifungal agents, in preventing aspergillosis has not been well 
evaluated.433,434,437-439 In one study of heart-transplant 
recipients, protective isolation of patients alone failed to prevent 
fungal infections.440
    The reported attributable mortality from invasive pulmonary 
aspergillosis has varied, depending on the patient population studied. 
Rates have been as high as 95% in recipients of allogeneic bone-marrow 
transplants and patients with aplastic anemia, compared with rates of 
13-80% in leukemic patients.441-443

II. Pathogenesis

    In contrast to most bacterial pneumonias, the primary route of 
acquiring Aspergillus sp. infection is by inhalation of the fungal 
spores. In severely immunocompromised patients, primary Aspergillus 
spp. pneumonia results from local lung tissue invasion.419,444,445 
Subsequently, the fungus may disseminate via the bloodstream to involve 
multiple other deep organs.419,445,446 A role for nasopharyngeal 
colonization with Aspergillus spp., as an intermediate step before 
invasive pulmonary disease, has been proposed, but remains to be 
elucidated.438,447,448 On the other hand, colonization of the 
lower respiratory tract by Aspergillus spp., especially in patients 
with preexisting lung disease such as chronic obstructive lung disease, 
cystic fibrosis, or inactive tuberculosis, has predisposed patients to 
invasive pulmonary and/or disseminated infection.419,445,449

III. Diagnosis

    Diagnosing pneumonia due to Aspergillus spp. is often difficult 
without performing invasive procedures. Bronchoalveolar lavage has been 
a useful screening test,450-452 but lung biopsy is still 
considered the most reliable technique.453 Histopathologic 
demonstration of tissue invasion by fungal hyphae has been required in 
addition to isolation of Aspergillus spp. from respiratory tract 
secretions because the latter, by itself, may indicate 
colonization.454 However, when Aspergillus spp. is grown from the 
sputum of a febrile, granulocytopenic patient with a new pulmonary 
infiltrate, it is highly likely that the patient has pulmonary 
aspergillosis.447,455 Routine blood cultures are remarkably 
insensitive for detecting Aspergillus spp.,456 and systemic 
antibody responses in immunocompromised patients are likely to be 
unreliable indicators of infection.457-459 Antigen-based serologic 
assays are now being developed in an attempt to allow for the rapid and 
specific diagnosis of Aspergillus spp. infections; however, their 
clinical usefulness is presently undefined.460,461

IV. Risk Factors and Control Measures

    The major risk factor for invasive aspergillosis is severe and 
prolonged granulocytopenia, both disease- and therapy-induced.462 
Since bone-marrow transplant recipients experience the most severe 
degree of granulocytopenia, they probably constitute the population at 
highest risk of developing invasive aspergillosis.442,463 The 
tendency of bone-marrow transplant recipients to develop severe 
granulocytopenia (<1,000 polymorphonuclears/l) is associated 
with the type of graft they receive. While both autologous and 
allogeneic bone-marrow transplant recipients are severely 
granulocytopenic for up to 4 weeks after the transplant procedure, 
allogeneic-transplant recipients may, in addition, develop acute or 
chronic graft-versus-host disease. The latter may occur up to several 
months after the procedure, and the disease and/or its therapy (often 
with high doses of corticosteroids, cyclosporine, and other 
immunosuppressive agents) may result in severe granulocytopenia. 
Consequently, in developing strategies to prevent invasive Aspergillus 
spp. infection in bone-marrow-transplant patients, infection control 
personnel should consider exposures of the patient to the fungus not 
only during the patient's immediate posttransplantation period, but 
also other exposures (e.g., at home or in an ambulatory-care setting) 
subsequent to the immediate posttransplant period, when the patient 
(especially allogeneic-transplant recipients) may again manifest severe 
granulocytopenia. To help address this problem, various studies are now 
in progress to evaluate newer methods of enhancing host resistance to 
invasive fungal (and other) infections, and of eliminating or 
suppressing respiratory fungal colonization of the upper respiratory 
tract. These methods include, respectively, the use of granulocyte-
colony-stimulating factors and intranasal application of amphotericin 
B, or oral or systemic antifungal drug prophylaxis.418,464-467 For 
solid-organ transplant recipients, risk factors for invasive 
aspergillosis have not been as extensively studied. In one study of 
liver-transplant recipients, risk factors for invasive infection with 
Aspergillus sp. identified by univariate analysis included preoperative 
and postoperative receipt of steroids and antimicrobial agents, and 
prolonged duration of transplant surgery.468
    The presence of aspergilli in the hospital environment is the major 
extrinsic risk factor for the occurrence of opportunistic invasive 
Aspergillus sp. infection.437,469 Environmental disturbances due 
to construction and/or renovation activities in and around hospitals 
markedly raise the airborne Aspergillus spp. spore counts in such 
hospitals and have been associated with nosocomial 
aspergillosis.426,428,429,470-473 In addition, aspergillosis in 
high-risk immunosuppressed patients has been associated with other 
hospital environmental reservoirs, including bird droppings in air 
ducts supplying high-risk patient areas,474 and contaminated 
fireproofing material or damp wood.428,475
    A single case of nosocomial Aspergillus spp. pneumonia is often 
difficult to link to a specific environmental exposure. However, 
additional cases may remain undetected without an active search that 
includes an intensive retrospective review of microbiologic, 
histopathologic, and postmortem records; notification of clinicians 
caring for high-risk patients; and establishment of a system for 
prospective surveillance for additional cases. When additional cases 
are detected, the likelihood is increased that a hospital environmental 
source of Aspergillus spp. can be identified.426,428,470-475 
Previous investigations have shown the importance of construction 
activities and/or fungal ``contamination'' of hospital air-handling 
systems as major sources for outbreaks.424,426,428,470-474 New 
molecular typing techniques, namely karyotyping476 and DNA 
endonuclease profiling (now available for A. fumigatus),477 may 
significantly aid in identifying the source of an outbreak.
    Outbreaks of invasive aspergillosis reinforce the importance of 
maintaining an environment as free of Aspergillus spp. spores as 
possible for patients with severe granulocytopenia. To achieve this 
goal, specialized services in many large hospitals, in particular bone-
marrow transplant services, have installed ``protected environments'' 
for the care of their high-risk, severely granulocytopenic patients, 
and increased their vigilance during hospital construction and routine 
maintenance of hospital air-filtration and ventilation systems, to 
prevent exposing high-risk patients to bursts of fungal 
spores.426,428,470-474,478-483
    While the exact configuration and specifications of the protected 
environments may vary between hospitals, these patient-care areas are 
built to minimize fungal spore counts in air by maintaining (a) high-
efficiency filtration of incoming air as it enters the room (i.e., at 
point of use) with HEPA filters that are 99.97% efficient in filtering 
0.3-sized particles, (b) directed room airflow--from intake on 
one side of the room, across the patient, and out through the exhaust 
on the opposite side of the room, (c) positive room-air pressure 
relative to the corridor, (d) well-sealed rooms, and (e) high rates of 
room-air changes (range: 15 to >400 per hour).424,479-481,483-485 
The oldest and most studied protected environment is a room with 
laminar airflow, consisting of a bank of HEPA filters along an entire 
wall through which air is pumped by blowers into the room at a uniform 
velocity (30-90 feet/minute), forcing the air to move in a laminar, or 
at least unidirectional, pattern.486 The air usually exits at the 
opposite end of the room, and ultra-high (100-400 per hour) air-change 
rates are achieved.424 The net effects are: essentially sterile 
air in the room, minimal air turbulence, minimal opportunity for 
microorganism build-up, and a consistently clean environment.424
    The efficacy of a laminar-airflow system in decreasing or 
eliminating the risk of nosocomial aspergillosis in high-risk patients 
has been demonstrated.424,479,484,485 However, such a system is 
costly to install and maintain.469 Less expensive alternative 
systems with lower air-change rates (10-15 per hour) have been utilized 
in some centers.480,481,487 However, studies comparing the 
efficacy of these alternative systems with laminar-airflow rooms in 
eliminating Aspergillus spp. spores and preventing nosocomial 
aspergillosis are limited. One institution employing cross-flow 
ventilation, point-of-use high-efficiency filters, and 15 air changes 
per hour reported that cases of nosocomial aspergillosis in patients 
housed in these rooms have occurred, albeit at a low rate 
(3.4%).481,487 The infections, however, were due to A. flavus--a 
species that was never cultured from the room air, suggesting that the 
patients were probably exposed to fungal spores when they were allowed 
outside their rooms.481
    Copper-8-quinolinolate has been used on environmental surfaces 
contaminated with Aspergillus spp. to control a reported 
outbreak,488 and incorporated in fireproofing material of a newly 
constructed hospital481 to help decrease the environmental spore 
burden, but its general applicability is yet to be established.

VIRAL PNEUMONIAS

    Viruses can be an important and often unappreciated cause of 
nosocomial pneumonia.489,490 In one prospective study of endemic 
nosocomial infections, approximately 20% of patients with pneumonia had 
viral infections.490} Although early diagnosis and treatment of 
viral infections have become possible in recent years,491-494 many 
hospitalized patients remain at high risk for developing severe and 
sometimes fatal viral infections.489,495-502 Based on these data 
and on well-documented outbreaks with nosocomial viral 
transmission,503-506  measures to prevent viral transmission 
should be instituted.
    Nosocomial respiratory viral infections (1) usually follow 
community outbreaks that occur during a particular period every 
year,505,507-510 (2) confer only short-term immunity,511 (3) 
affect healthy and ill persons,497,498,504,512-514 and (4) have 
exogenous sources. A number of viruses, including adenoviruses, 
influenza virus, measles virus, parainfluenza viruses, respiratory 
syncytial virus (RSV), rhinoviruses, and varicella-zoster virus can 
cause nosocomial pneumonia;498,505,506,515-521 however, 
adenoviruses, influenza or parainfluenza viruses, and RSV have been 
reported to account for most (70%) of nosocomial pneumonias due to 
viruses.522,523
    Because influenza and RSV infections account for a substantial 
portion of morbidity and mortality due to viral pneumonia and have been 
well studied epidemiologically, this section focuses on the principles 
and approaches to control these infections. However, because the modes 
of transmission of RSV (i.e., by large droplets or by contact with 
contaminated hands or other fomites) are the same as those of 
parainfluenza viruses and similar to those of adenoviruses and 
rhinoviruses (i.e., mainly by large droplets or contact with 
contaminated hands or other fomites, but also possibly by aerosol 
inhalation), infection-control measures recommended for RSV infection 
are applicable to infections caused by the other three 
viruses.524-529 Prevention of nosocomial infections due to measles 
and varicella-zoster is addressed in another document.213

RSV INFECTION

I. Epidemiology

    RSV infection is most common during infancy and early childhood, 
but may also occur in adults.134,512,515,530,531 Infection usually 
causes mild or moderately severe upper respiratory illness. However, 
life-threatening pneumonia or bronchiolitis has been reported in 
children with chronic cardiac and pulmonary disease, immunocompromised 
patients, and the elderly.497,499,514,515,532,533
    Recent surveillance of 10 U.S. hospital laboratories performing 
cultures for RSV suggests that community outbreaks occur yearly between 
December and March, last from 3-5 months, and are associated with 
increased hospitalization and deaths among infants and young 
children.534 During community outbreaks of RSV, children admitted 
to the hospital with respiratory symptoms often serve as reservoirs for 
RSV.503,505

II. Diagnosis

    The clinical characteristics of RSV infection, especially in 
neonates, are often indistinguishable from those of other viral 
respiratory tract infections.515,516 Culture of RSV from 
respiratory secretions remains the ``gold standard'' for diagnosis. 
Although rapid antigen-detection kits utilizing direct 
immunofluorescence or enzyme-linked immunosorbent assay are available 
and can provide results within hours, the benefit of using these tests 
to identify infected and susceptible patients depends on the 
sensitivity and specificity of the test. The reported sensitivity and 
specificity of RSV enzyme immunoassays vary between 80% and 95%, and 
may even be lower in actual practice.535-538 In general, once 
laboratory-confirmed cases of RSV infection are identified in a 
hospital, a presumptive diagnosis of RSV infection in subsequent cases 
with manifestations suggestive of RSV infection may be acceptable for 
infection control purposes.

III. Modes of Transmission

    RSV is present in large numbers in the respiratory secretions of 
symptomatic persons infected with the virus and can be transmitted 
directly via large droplets during close contact with such persons, or 
indirectly via RSV-contaminated hands or fomites.503,524,525 The 
portal of entry is usually the conjunctiva or the nasal mucosa.526 
Inoculation by RSV-contaminated hands is the usual way of depositing 
the virus onto the eyes or nose.503,524-526 Hands can become 
contaminated through handling of infected persons' respiratory 
secretions or contaminated fomites.524,525
    In nosocomial RSV outbreaks in which the viral isolates were typed, 
more than one strain of RSV has often been identified,504,513,539 
suggesting multiple sources of the virus. Potential sources include 
patients, hospital staff, and visitors. Because infected infants shed 
large amounts of virus in their respiratory secretions and easily 
contaminate their immediate surroundings, they are a major reservoir 
for RSV.540 Hospital staff may become infected after exposure in 
the community541 or in the hospital, and in turn, infect patients, 
other health-care workers, or hospital visitors.516,542

IV. Control Measures

    Various combinations of control measures ranging from the simple to 
the complex have been effective, to some degree or other, in preventing 
and controlling nosocomial RSV infection.215,542-549 Successful 
programs have had two elements in common: implementation of contact-
isolation precautions, and compliance with these precautions by 
healthcare personnel. In theory, strict handwashing should prevent most 
nosocomial RSV infections. However, health-care workers' handwashing 
practices have always been poor, even in institutions with good 
educational programs.210,211 Thus, other preventive measures are 
usually relied upon to prevent RSV infection.
    The basic precautions that have been associated with decreased 
incidence of nosocomial RSV infections are gloving and gowning.215 
Gloving has helped decrease transmission probably because gloves remind 
patient-care personnel to comply with handwashing and other 
precautions, and deter persons from touching their eyes or noses. The 
benefits from gloving, however, are offset if gloves are not changed 
between patients or after contact with contaminated fomites, and if 
hands are not adequately washed after glove removal.218 Gowning, 
in combination with gloving, during contact with RSV-infected infants 
or their immediate environment has been used successfully to prevent 
infection.215 In addition, the use of eye-nose goggles rather than 
masks has protected healthcare workers from infection; however, eye-
nose goggles are not widely available and are inconvenient to 
wear.546,550
    Additional measures may be indicated to control ongoing nosocomial 
transmission of RSV or to prevent transmission to patients at high risk 
for serious complications of infections, such as those with compromised 
cardiac, pulmonary, or immune systems. The following additional control 
measures have been used in various combinations: (1) Use of private 
rooms for infected patients OR cohorting of infected patients, with or 
without pre-admission screening by rapid laboratory diagnostic tests, 
(2) cohorting of personnel, (3) exclusion of healthcare workers who 
have symptoms of upper respiratory tract infection from the care of 
uninfected patients at high risk of severe or fatal RSV infection, 
e.g., infants, (4) limiting visitors, and (5) postponing admission of 
patients at high risk of complications from RSV 
infection.213,543,545,547,549 Although the exact role of each of 
these measures has not been fully elucidated, their use for control of 
outbreaks seems prudent.

INFLUENZA

I. Epidemiology

    Pneumonia in patients with influenza may be due to the influenza 
virus itself, secondary bacterial infection, or a combination of 
both.551-553 Influenza-associated pneumonia can occur in any 
person, but is more common in the very young or old and in persons in 
any age group with immunosuppression or certain chronic medical 
conditions such as severe underlying heart or lung 
disease.531,554-556
    Influenza typically occurs annually in the winter between December 
and April; peak activity in a community usually lasts from 6 to 8 weeks 
during this period.557,558 During influenza epidemics in the 
community, nosocomial outbreaks may occur and are characterized by 
abrupt onset and rapid transmission.559-561 Most reported 
institutional outbreaks of influenza have occurred in nursing homes; 
however, hospital outbreaks have been reported on pediatric and 
chronic-care wards, as well as on medical and neonatal intensive care 
units.506,562-565
    Influenza is believed to be spread from person to person by direct 
deposition of virus-laden large droplets onto the mucosal surfaces of 
the upper respiratory tract of an individual during close contact with 
an infected person, as well as by droplet nuclei or small-particle 
aerosols.566-569 The extent to which transmission may occur by 
virus-contaminated hands or fomites is unknown; however, it is not the 
primary mode of spread.570
    The most important reservoirs of influenza virus are infected 
persons, and the period of greatest communicability is during the first 
3 days of illness; however, the virus can be shed before onset of 
symptoms, and up to 7 or more days after illness onset.506,557,571

II. Diagnosis

    Influenza is clinically indistinguishable from other febrile 
respiratory illnesses, but during outbreaks with laboratory-confirmed 
cases, a presumptive diagnosis of the infection can be made in cases 
with similar manifestations.572 In the past, diagnosis of 
influenza was made by virus isolation from nasopharyngeal secretions or 
by serologic conversion, but recently developed rapid diagnostic tests 
that are similar to culture in sensitivity and specificity allow early 
diagnosis and treatment of cases and provide a basis for prompt 
initiation of antiviral prophylaxis as part of outbreak 
control.573-578

III. Prevention and Control Measures

    Vaccination of persons at high risk for complications of influenza 
is currently the most effective measure for reducing the impact of 
influenza, and should be done before the influenza season each year. 
Such persons include those 65 years of age; those in long-
term-care units; those with chronic disorders of the pulmonary or 
cardiovascular systems, those with diabetes mellitus, renal 
dysfunction, hemoglobinopathies, musculo-skeletal disorders, or 
immunosuppression; and children 6 months-18 years of age who are 
receiving long-term aspirin therapy.564,579-581 When high 
vaccination rates are achieved in closed or semi-closed settings, the 
risk of outbreaks is reduced because of induction of herd 
immunity.582,583
    When an institutional outbreak is due to influenza A, antiviral 
agents may be used both for treatment of ill persons and as prophylaxis 
for others.584 Two related antiviral agents, amantadine 
hydrochloride and rimantadine hydrochloride, are effective against 
influenza-A, but not influenza-B, virus.493,585-587 These agents 
can be used (1) for short-term prophylaxis after late vaccination of 
high-risk persons; (2) as prophylaxis for persons for whom vaccination 
is contraindicated; (3) as prophylaxis for immunocompromised persons 
who may not produce protective levels of antibody in response to 
vaccination; (4) for prophylaxis for unvaccinated healthcare workers 
who provide care to high-risk patients, either for the duration of 
influenza activity in the community or until immunity develops after 
vaccination; and (5) when vaccine strains do not closely match the 
epidemic viral strain.584
    Amantadine has been available in the United States for many years; 
rimantadine has just recently been approved for use. Both drugs protect 
against all naturally-occurring strains of type A influenza virus; 
thus, antigenic changes in the virus that may reduce vaccine efficacy 
do not alter the effectiveness of amantadine or rimantadine. Both are 
70-90% effective in preventing illness if taken before exposure to 
influenza A virus.585,588 In addition, they lessen the severity 
and duration of illness due to influenza A when administered within 24-
48 hours after onset of symptoms.589,590 Amantadine can limit 
nosocomial spread of influenza A if it is administered to all or most 
patients at the time influenza is recognized in a 
facility.562,591,592
    Side effects from amantadine are more common than those from 
rimantadine; they include mild and transitory nervousness, insomnia, 
impaired concentration, mood changes, light-headedness, anorexia, and 
nausea. These symptoms have been reported in 5-10% of healthy young 
adults receiving 200 mg of the drug per day.493,585 In the 
elderly, the symptoms may be more severe; in addition, dizziness and 
ataxia are more common in this age group.593,594 Thus, it is 
recommended that for persons 65 years of age and/or those 
who have renal insufficiency, amantadine dosage should be reduced to 
100 mg per day. Further reductions are recommended on the 
basis of the patient's creatinine clearance.595,596 However, 
because recommended dosages based on creatinine clearance may provide 
only a rough estimate of the optimal dose for a given patient,597 
such persons should be carefully observed so that adverse reactions can 
be recognized promptly and the dose further reduced or the drug 
discontinued, if necessary.
    Emergence of amantadine- and rimantadine-resistant strains of 
influenza A virus has been observed in persons who receive these drugs 
for treatment of the infection.598,599 Because of the potential 
risk of transmission of resistant viral strains to close contacts of 
persons receiving amantadine or rimantadine for treatment,599,600 
to the extent possible, infected persons taking either drug should 
avoid contact with others during treatment and for 2 days after 
discontinuing treatment.600,601 This is particularly important if 
the contacts are uninfected persons taking amantadine or rimantadine 
for prophylaxis.600,602
    Vaccination of high-risk patients and of hospital personnel before 
the influenza season is the primary focus of efforts to prevent and 
control nosocomial influenza.581,584,603 The decision to use 
amantadine or rimantadine as an adjunct to vaccination in the 
prevention and control of nosocomial influenza is based in part on 
results of virologic and epidemiologic surveillance in the hospital and 
the community. When outbreaks of influenza A occur in a hospital, and 
antiviral prophylaxis of high-risk persons and treatment of cases is 
undertaken, administration of amantadine or rimantadine is begun as 
early in the outbreak as possible to reduce 
transmission.562,584,591,602
    Measures other than vaccination and chemoprophylaxis with 
amantadine or rimantadine have been recommended for control of 
nosocomial influenza outbreaks. Because influenza can be transmitted 
during contact with an infected person, contact-isolation precautions, 
such as placing a patient symptomatic with influenza in a private room, 
cohorting of patients with influenza, and masking upon entering a room 
with persons with influenza have been recommended.213 Handwashing, 
gloving, and gowning by healthcare workers during the period of viral 
shedding by patients have also been recommended, but the exact role of 
these measures in preventing influenza transmission remains to be 
elucidated.213,561,604 Although influenza can be transmitted via 
the airborne route, the efficacy of placing infected persons in rooms 
with negative pressure in relation to their immediate environment has 
not been assessed. In addition, this measure may be impractical during 
institutional outbreaks that occur in the midst of a community epidemic 
of influenza because many newly admitted patients and healthcare 
workers may be infected with the virus; thus, the hospital would face 
the logistical problem of accommodating all ill persons in rooms with 
special ventilation. Although controlled studies are not available to 
measure their effectiveness, the following additional measures have 
been recommended for consideration, particularly during severe 
outbreaks: (1) Curtailment or elimination of elective admissions, both 
medical and surgical; (2) restriction of cardiovascular and pulmonary 
surgery; (3) restriction of hospital visitors, especially those with 
acute respiratory illnesses; and (4) work restriction for healthcare 
workers with acute respiratory illness.604

PART II. RECOMMENDATIONS FOR PREVENTION OF NOSOCOMIAL PNEUMONIA

Introduction

    The recommendations are presented according to the etiology of the 
infection, in the following order: bacterial pneumonia, including 
Legionnaires' disease; fungal pneumonia (aspergillosis); and virus-
associated pneumonia (RSV and influenza infections). Each topic is 
subdivided according to the following general approaches for nosocomial 
infection control, as applicable to the infection:
    1. Staff education and infection surveillance;
    2. Interruption of transmission of microorganisms by eradicating 
infecting; microorganisms from their epidemiologically important 
reservoirs, and/or preventing person-to-person transmission; and
    3. Modifying host risk for infection.
    As in previous CDC guidelines, each recommendation is categorized 
on the basis of existing scientific evidence, theoretical rationale, 
applicability, and economic impact.213,214,605-609 However, the 
previous CDC system of categorizing recommendations has been modified 
as follows:
    CATEGORY IA--Strongly recommended for all hospitals and strongly 
supported by well-designed experimental or epidemiologic studies.
    CATEGORY IB-- Strongly recommended for all hospitals and viewed as 
effective by experts in the field and a consensus of HICPAC based on 
strong rationale and suggestive evidence, even though definitive 
scientific studies may not have been done.
    CATEGORY II--Suggested for implementation in many hospitals. 
Recommendations may be supported by suggestive clinical or 
epidemiologic studies, a strong theoretical rationale, or definitive 
studies applicable to some but not all hospitals.
    NO RECOMMENDATION; UNRESOLVED ISSUE. Practices for which 
insufficient evidence or consensus regarding efficacy exists.

Prevention and Control of Bacterial Pneumonia

I. Staff Education and Infection Surveillance

A. Staff Education

    Educate healthcare workers regarding nosocomial bacterial 
pneumonias and infection control procedures to prevent their 
occurrence.610-613
CATEGORY IA

B. Surveillance

    1. Conduct surveillance for bacterial pneumonia in ICU patients at 
high-risk for nosocomial bacterial pneumonia (e.g., patients with 
mechanically assisted ventilation, selected postoperative patients) to 
determine trends and identify potential 
problems.7,34,35,59,60,614-616 Include data regarding the 
causative microorganisms and their antimicrobial susceptibility 
patterns.2-4 Express data as rates (e.g., number of infected 
patients or infections per 100 ICU days or per 1,000 ventilator-days) 
to facilitate intra- and inter-hospital comparisons.63,617-619
CATEGORY IA
    2. Do not routinely perform surveillance cultures of patients or of 
equipment or devices used for respiratory therapy, pulmonary-function 
testing, or delivery of inhalation anesthesia.62,620,621
CATEGORY IA

II. INTERRUPTION OF TRANSMISSION OF MICROORGANISMS

A. Sterilization or Disinfection, and Maintenance of Equipment and 
Devices

1. General Measures
    a. Thoroughly clean all equipment and devices to be sterilized or 
disinfected. Decontaminate equipment or device before or during 
cleaning if it is contaminated with blood and/or marked 
``contaminated'' and received from patients who are on certain types of 
isolation.245,246,622
CATEGORY IA
    b. Sterilize semicritical equipment or devices, i.e., items that 
touch mucous membranes (See device list, Appendix A). If sterilization 
is not feasible, use high-level disinfection either by wet heat 
pasteurization (76 deg.C for 30 minutes), or by using liquid 
disinfectants approved as sterilants or disinfectants by the 
Environmental Protection Agency.240,242,244,246,623 Follow 
disinfection with appropriate rinsing, drying, and packaging, taking 
care not to contaminate the items in the process.
CATEGORY IB
    c. Use sterile (not distilled, nonsterile), pyrogen-free water for 
rinsing reusable equipment and devices after they have been chemically 
disinfected.227,233,234,248
CATEGORY IB
    d. Do not reprocess an equipment or device that is manufactured for 
single use only, unless data show that reprocessing the equipment or 
device poses no threat to the patient, is cost-effective, and does not 
change the structural integrity or function of the equipment or 
device.624,625
CATEGORY IB
2. Mechanical Ventilators, Anesthesia Machines and Circle Systems, and 
Pulmonary-Function Testing Equipment
    a. Do not routinely sterilize or disinfect the internal machinery 
of mechanical ventilators or anesthesia-breathing machines and their 
circle systems.626,627
CATEGORY IA
    b. Do not routinely sterilize or disinfect the internal machinery 
of pulmonary-function testing machines between uses on different 
patients.628,629
CATEGORY II
3. Ventilator Circuits with Humidifiers
    a. Do not routinely change more frequently than every 48 hours the 
breathing circuit, including tubing and exhalation valve, and the 
attached bubbling or wick humidifier of a ventilator that is in use on 
an individual patient.34,257,262
CATEGORY IA
    b. NO RECOMMENDATION for the maximum length of time after which the 
breathing circuit and the attached bubbling or wick humidifier of a 
ventilator in use on a patient should be changed.263
UNRESOLVED ISSUE
    c. Sterilize reusable breathing circuits and bubbling or wick 
humidifiers, or subject them to high-level disinfection between their 
uses on different patients.240,242,244,246
CATEGORY IB
    d. Periodically drain and discard any condensate that collects in 
the tubing of a mechanical ventilator or anesthesia machine, taking 
precautions not to allow condensate to drain toward the patient. Wash 
hands after performing the procedure or handling the fluid.256,260
CATEGORY IB
    e. NO RECOMMENDATION for placing a filter or trap at the distal end 
of the expiratory-phase tubing of the breathing circuit to collect 
condensate.231,256
UNRESOLVED ISSUE
    f. Do not place bacterial filters between the humidifier reservoir 
and the inspiratory-phase tubing of the breathing circuit of a 
mechanical ventilator, or in the circuit of an anesthesia 
machine.254,627,630
CATEGORY IB
    g. Humidifier fluids.
    (1) Use sterile water to fill bubbling humidifiers.125,233,234,260
CATEGORY II
    (2) Use sterile, distilled, or tap water to fill wick 
humidifiers.233,234,260
CATEGORY II
    (3) NO RECOMMENDATION for preferential use of a closed, continuous-
feed humidification system.
UNRESOLVED ISSUE
4. Ventilator Circuits With Hygroscopic Condenser-Humidifiers or Heat-
Moisture Exchangers
    a. NO RECOMMENDATION for preferential use of hygroscopic condenser-
humidifier or heat-moisture exchanger rather than a heated humidifier 
to prevent nosocomial pneumonia.272-276
UNRESOLVED ISSUE
    b. Change the hygroscopic condenser-humidifier or heat-moisture 
exchanger when evidence of gross contamination or mechanical 
dysfunction of the device is present.272
CATEGORY IB
    c. Do not routinely change the breathing circuit attached to a 
hygroscopic condenser-humidifier or heat-moisture exchanger while it is 
in use on a patient.272,275
CATEGORY IB
5. Wall Humidifiers
    a. Follow manufacturers' instructions for use and maintenance of 
disposable wall oxygen humidifiers unless data show that the 
modification in their use or maintenance poses no threat to the patient 
and is cost effective.631-635
CATEGORY IB
    b. Between patients, change the reservoir, tubing (including any 
nasal prongs), and any mask used to deliver oxygen from a wall outlet.
CATEGORY IB
6. Small-Volume Medication Nebulizers: ``In-Line'' and Hand-Held 
Nebulizers
    a. Between treatments on the same patient, disinfect or rinse with 
sterile water and air-dry small-volume medication 
nebulizers.228,378
CATEGORY IB
    b. Replace nebulizers between patients with those that have 
undergone sterilization or high-level disinfection.119,121,122,248
CATEGORY IB
    c. Use only sterile fluids for nebulization, and dispense these 
fluids aseptically.223,227,233,234,248,278,378
CATEGORY IA
    d. If multi-dose medication vials are used, handle, dispense, and 
store them according to directions on the vial label or package 
insert.278,636,637
CATEGORY IB
7. Large-Volume Nebulizers and Mist Tents
    a. Do not use large-volume room-air humidifiers that create 
aerosols (e.g., by venturi principle, ultrasound, or spinning disk) and 
thus are really nebulizers, unless they can be sterilized or subjected 
to high level disinfection at least daily and filled only with sterile 
water.224,225,227,236,277,638
CATEGORY IA
    b. Sterilize large-volume nebulizers that are used for inhalation 
therapy, e.g., for tracheostomized patients, or subject them to high-
level disinfection between patients and after every 24 hours of use on 
the same patient.119,121,122
CATEGORY IB
    c. Use mist-tent nebulizers and reservoirs that have undergone 
sterilization or high-level disinfection, and replace them between 
patients and after every 24 hours of use on the same patient.\639\
CATEGORY IB
8. Other Devices
    a. Between patients, sterilize or use high-level disinfection on 
respirometers, oxygen sensors, and other respiratory devices used on 
multiple patients.220,286
CATEGORY IB
    b. Sterilize or use high-level disinfection on hand-powered 
resuscitation bags (for example, Ambu bags) between 
patients.239,283-285
CATEGORY IA
    c. Remove faucet aerators.\640\
CATEGORY II

B. Interruption of Person-to-Person Transmission of Bacteria

1. Handwashing
    Wash hands after contact with mucous membranes, respiratory 
secretions, or objects contaminated with respiratory secretions, 
whether or not gloves are worn. Wash hands before and after contact 
with a patient who has an endotracheal or tracheostomy tube in place, 
and before and after contact with any respiratory device that is used 
on the patient, whether or not gloves are 
worn.201,203,207,208,641,642
CATEGORY IA
2. Barrier Precautions
    a. Wear gloves for handling respiratory secretions or objects 
contaminated with respiratory secretions of any patient.215,216
CATEGORY IA
    b. Change gloves and wash hands between patients; after handling 
respiratory secretions or objects contaminated with secretions from one 
patient and before contact with another patient, object, or 
environmental surface; and between contacts with a contaminated body 
site and respiratory tract of, or respiratory device on, the same 
patient.215,217,218
CATEGORY IA
    c. Wear a gown when soiling with respiratory secretions from a 
patient is anticipated, and change the gown after such contact and 
before providing care to another patient.215
CATEGORY IB
3. Care of Patients with Tracheostomy
    a. Perform tracheostomy under sterile conditions.
CATEGORY IB
    b. When changing a tracheostomy tube, use aseptic technique and 
replace the tube with one that has undergone sterilization or high-
level disinfection.
CATEGORY IB
4. Suctioning of Respiratory Tract Secretions
    a. NO RECOMMENDATION for wearing sterile rather than clean gloves 
when suctioning a patient's respiratory secretions.
UNRESOLVED ISSUE 
    b. If the open suction system is employed, use a sterile single-use 
catheter.
CATEGORY II
    c. Use only sterile fluid to remove secretions from the suction 
catheter.
CATEGORY IB 
    d. Change suction-collection tubing and canisters between patients.

Category IB 

    e. NO RECOMMENDATION for using a multi-use closed-system suction 
catheter in preference to a single-use open-system catheter.279-
282
UNRESOLVED ISSUE 
    f. NO RECOMMENDATION for routinely using an endotracheal tube with 
a dorsal lumen above the endotracheal cuff, to allow drainage (by 
suctioning) of tracheal secretions that accumulate in the patient's 
subglottic area.197
UNRESOLVED ISSUE

III. Modifying Host Risk for Infection

A. Precautions for Prevention of Endogenous Pneumonia

1. Prevention of Aspiration
    a. Discontinue enteral-tube feeding and remove devices such as 
endotracheal and/or nasogastric or other enteral tubes from patients as 
soon as the clinical indications for these are 
resolved.7,34,35,80,110,173,175,176,192,643
CATEGORY IB
    b. If there is no contraindication to the maneuver, elevate at an 
angle of 30-45 deg. the head of the bed of a patient who is receiving 
mechanically assisted ventilation and has a nasogastric or other 
enteral tube in place.175,184

CATEGORY IB

    c. Routinely verify appropriate placement of the feeding 
tube.175644-646
CATEGORY IB

    d. Routinely assess the patient's intestinal motility, (e.g., by 
auscultating for bowel sounds and measuring residual gastric volume or 
abdominal girth) and adjust the rate and volume of enteral feeding to 
avoid regurgitation.175,188,643

CATEGORY IB

    e. Use small-bore tubes for enteral 
feeding;175,176,186,644,647

CATEGORY II

    f. Administer enteral feeding intermittently in small quantities, 
rather than continuously.2T167,183,647,648

CATEGORY II

    g. NO RECOMMENDATION for preferentially placing the feeding tubes, 
e.g., jejunal tubes, distal to the pylorus;189,190,649

UNRESOLVED ISSUE

    h. NO RECOMMENDATION for using oro-tracheal rather than naso-
tracheal tube.650

UNRESOLVED ISSUE

2. Prevention of Gastric Colonization
    a. If stress-bleeding prophylaxis is needed for a patient with 
mechanically assisted ventilation, use an agent that does not raise the 
patient's gastric pH.22,34,105,111,115,140-142,144-146
Category II
    b. NO RECOMMENDATION for selective decontamination of an ICU 
patient's digestive tract with oral and/or intravenous antimicrobials 
to prevent gram-negative bacillary (or Candida spp.) 
pneumonia.147-170
UNRESOLVED ISSUE
    c. NO RECOMMENDATION for routine acidification of gastric 
feedings.171
UNRESOLVED ISSUE

B. Prevention of Postoperative Pneumonia

    1. Instruct preoperative patients, especially those at high risk of 
developing pneumonia, regarding frequent coughing, taking deep breaths, 
and ambulating as soon as medically indicated in the postoperative 
period.302,304 High-risk patients include those who will receive 
anesthesia, especially those who will have an abdominal, thoracic, 
head, or neck operation, or who have substantial pulmonary dysfunction, 
such as patients with chronic obstructive lung disease, a 
musculoskeletal abnormality of the chest, or abnormal pulmonary 
function tests.287-290,293,294
CATEGORY IB
    2. Encourage postoperative patients to cough frequently, take deep 
breaths, move about the bed, and ambulate unless it is medically 
contraindicated.301,302,304
CATEGORY IB
    3. Control pain that interferes with coughing and deep breathing 
during the immediate postoperative period by using systemic 
analgesia,309,652 including patient-controlled analgesia,310-
312 with as little cough-suppressant effect as possible; appropriate 
support for abdominal wounds, such as tightly placing a pillow across 
the abdomen; or regional (e.g., epidural) analgesia.313-315
CATEGORY IB
    4. Use an incentive spirometer or intermittent positive pressure 
breathing, perform chest physiotherapy on patients at high risk of 
developing postoperative pneumonia.295,298,299,302,304,305,307 
(See III-B-1 above for definition of high-risk patients.)
CATEGORY II

C. Other Prophylactic Procedures for Pneumonia

1. Vaccination of Patients
    Vaccinate patients at high risk for complications of pneumococcal 
infections with pneumococcal polysaccharide vaccine. High-risk patients 
include persons 65 years old; adults with chronic 
cardiovascular or pulmonary disease, diabetes mellitus, alcoholism, 
cirrhosis, or cerebrospinal fluid leaks; and children and adults with 
immunosuppression, functional or anatomic asplenia, or HIV 
infection.319-321
CATEGORY IA
2. Systemic Antimicrobial Prophylaxis
    Do not routinely administer systemic antimicrobial agents to 
prevent nosocomial pneumonia.84,191,322-325,653
CATEGORY IA
3. Use of Rotating ``Kinetic'' Beds
    NO RECOMMENDATION for the use of continuous lateral rotational 
therapy (i.e., placing patients on ``kinetic'' beds that turn on their 
longitudinal axes continuously and slowly) for prevention of nosocomial 
pneumonia in patients in the ICU, critically ill patients, or patients 
immobilized by illness and/or trauma.327-332
UNRESOLVED ISSUE

Prevention and Control of Legionnaires' Disease

I. Staff Education and Infection Surveillance

A. Staff Education

    Educate (1) physicians and nurses to heighten their suspicion for 
cases of nosocomial Legionnaires' disease and to use appropriate 
methods for its diagnosis, and (2) patient-care, infection-control, and 
engineering personnel about measures to control nosocomial 
legionellosis.611-613
CATEGORY IA

B. Surveillance

    1. Establish mechanism(s) to provide clinicians with appropriate 
laboratory tests for the diagnosis of Legionnaires' 
disease.339,367,368,372,654
CATEGORY IA
    2. Conduct active search for cases of nosocomial Legionnaires' 
disease, especially in patients who are at high-risk of acquiring the 
disease (patients who are immunosuppressed, including organ-transplant 
patients, patients with AIDS, and patients receiving systemic steroids; 
are 65 years of age; or have chronic underlying disease such 
as diabetes mellitus, congestive heart failure, and chronic obstructive 
lung disease).338,339,353,355-359,365 Refer to the accompanying 
background document for definition of nosocomial legionellosis.
CATEGORY II
    3. NO RECOMMENDATION for routinely culturing water systems for 
Legionella spp.250,338,383,387-389,391-393,408,655
UNRESOLVED ISSUE

II. Interruption of Transmission of Legionella SPP.

A. Primary Prevention (Preventing Nosocomial Legionnaires' Disease When 
No Cases Have Been Documented)

1. Nebulization and Other Devices
    a. Use only sterile (not distilled, nonsterile) water for rinsing 
nebulization devices and other respiratory-care equipment after they 
have been cleaned and/or disinfected.250,656
CATEGORY IB
    b. Use only sterile (not distilled, nonsterile) water to fill 
reservoirs of devices used for nebulization.227,236,250,378,656
CATEGORY IA
    c. Do not use large-volume room-air humidifiers that create 
aerosols (e.g., by venturi principle, ultrasound, or spinning disk) and 
thus are really nebulizers, unless they can be sterilized or subjected 
to high-level disinfection daily and filled only with sterile 
water.236,656
CATEGORY IA
2. Cooling Towers
    a. When a new hospital building is constructed, place cooling 
tower(s) in such a way that the tower drift is directed away from the 
hospital's air-intake system, and design the cooling towers such that 
the volume of aerosol drift is minimized.375,657
CATEGORY IB
    b. For operational cooling towers, install drift eliminators, 
regularly use an effective biocide, maintain the tower according to 
manufacturers' recommendations, and keep adequate maintenance 
records.375,415,658
CATEGORY IB
3. Water-Distribution System
    a. NO RECOMMENDATION for routinely maintaining potable water at the 
outlet at 50 deg.C or <20 deg.C, or chlorinating heated 
water to achieve 1-2 mg/L free residual chlorine at the 
tap.338,383,393,400-403
UNRESOLVED ISSUE
    b. NO RECOMMENDATION for treatment of water with ozone, ultraviolet 
light, or heavy-metal ions.344,411,412,414
UNRESOLVED ISSUE

B. Secondary Prevention (Response to Identification of Laboratory-
Confirmed Nosocomial Legionellosis)

    When a single case of laboratory-confirmed, definite nosocomial 
Legionnaires' disease is identified, OR if two or more cases of 
laboratory-confirmed, possible nosocomial Legionnaires' disease occur 
within 6 months of each other (Refer to background document for 
definition of definite and possible nosocomial Legionnaires' disease.):
    1. Contact the local or state health department or the CDC for 
consultation.
CATEGORY IB
    2. If a case is identified in a severely immunocompromised patient 
such as an organ-transplant recipient, OR if the hospital houses 
severely immunocompromised patients, conduct a combined epidemiologic 
and environmental investigation (as outlined from II-B-3-b-1 through 
II-B-5, below) to determine the source(s) of Legionella sp.
CATEGORY IB
    3. If the hospital does not house severely immunocompromised 
patients, conduct an epidemiologic investigation via a retrospective 
review of microbiologic, serologic, and postmortem data, and an 
intensive prospective surveillance for additional cases of nosocomial 
Legionnaires' disease.
CATEGORY IB
    a. If there is no evidence of continued nosocomial transmission, 
continue the intensive prospective surveillance (as in II-B-3, above) 
for at least 2 months after surveillance was begun.
CATEGORY II
    b. If there is evidence of continued transmission:
    (1) Conduct an environmental investigation to determine the 
source(s) of Legionella sp. by collecting water samples from potential 
sources of aerosolized water, following the methods described in 
Appendix C and saving and subtyping isolates of Legionella spp. 
obtained from patients and environment.227,375-382,404,406
CATEGORY IB
    (2) If a source is not identified, continue surveillance for new 
cases for at least 2 months, and, depending on the scope of the 
outbreak, decide on either deferring decontamination pending 
identification of the source(s) of Legionella spp., or proceeding with 
decontamination of the hospital's water distribution system, with 
special attention to the specific hospital areas involved in the 
outbreak.
CATEGORY II
    (3) If a source of infection is identified by epidemiologic and 
environmental investigation, promptly decontaminate it.417
CATEGORY IB
    (a) If the heated-water system is implicated:
    i. Decontaminate the heated-water system either by superheating 
(flushing for at least 5 minutes each distal outlet of the system with 
water at 65 deg.C), OR by hyperchlorination (flushing for at 
least 5 minutes all outlets of the system with water containing 
10 mg/L free residual chlorine).403,408-410 Post 
warning signs at each outlet being flushed to prevent scald injury to 
patients, staff, or visitors.
CATEGORY IB
    ii. Depending on local and state regulations regarding potable-
water temperature in public buildings, maintain potable water at the 
outlet at 50 deg.C or <20 deg.C, or chlorinate heated water 
to achieve 1-2 mg/L free residual chlorine at the tap in hospitals 
housing patients who are at high risk of acquiring nosocomial 
legionellosis (e.g., immunocompromised patients).338,383,393,400-
403 (See appendix B.)
CATEGORY II
    iii. NO RECOMMENDATION for treatment of water with ozone, 
ultraviolet light, or heavy-metal ions.344,411,412,414
UNRESOLVED ISSUE
    iv. Clean hot-water storage tanks and water-heaters to remove 
accumulated scale and sediment.346
CATEGORY IB
    v. Restrict immunocompromised patients from taking showers, and use 
only sterile water for their oral consumption until Legionella spp. 
becomes undetectable by culture in the hospital water.384
CATEGORY II
    (b) If cooling towers or evaporative condensers are implicated, 
decontaminate the cooling-tower system using the protocol outlined in 
Appendix D.415
CATEGORY IB
    (4) Assess the efficacy of implemented measures in reducing or 
eliminating Legionella spp. by collecting specimens for culture at 2-
week intervals for 3 months.
CATEGORY II
    (a) If Legionella sp. is not detected in cultures during 3 months 
of monitoring, collect cultures monthly for another 3 months.
CATEGORY II
    (b) If Legionella sp. is detected in one or more cultures, reassess 
the implemented control measures, modify them accordingly, and repeat 
decontamination procedures. Options for repeat decontamination include 
the intensive use of the same technique utilized for initial 
decontamination, or a combination of superheating and 
hyperchlorination.
CATEGORY II
    (5) Keep adequate records of all infection control measures, 
including maintenance procedures, and of environmental test results for 
cooling towers and potable-water systems.
CATEGORY II

Prevention and Control of Nosocomial Pulmonary Aspergillosis

I. Staff Education and Infection Surveillance

A. Staff Education

    Educate healthcare workers regarding nosocomial pulmonary 
aspergillosis especially in immunocompromised patients, and about 
infection control procedures to decrease its occurrence.611-613
CATEGORY IA

B. Surveillance

    1. Maintain a high index of suspicion for diagnosis of nosocomial 
pulmonary aspergillosis in high-risk patients (i.e., patients with 
prolonged, severe granulocytopenia [<1,000 polymorphonuclear cells/
mm3 for 2 weeks or <100 polymorphonuclear cells/mm3 for 1 
week]), such as organ-transplant recipients or patients with 
hematologic malignancies who are receiving 
chemotherapy.435,462,463,659
CATEGORY IB
    2. Maintain surveillance for cases of nosocomial pulmonary 
aspergillosis by periodically reviewing the hospital's microbiologic, 
histopathologic, and postmortem data.
CATEGORY IB
    3. NO RECOMMENDATION for routine, periodic culturing of the 
nasopharynx of high-risk patients,437,438 or devices, air samples, 
dust, ventilation ducts, and filters in rooms occupied by high-risk 
patients.418,428,437,471-473
UNRESOLVED ISSUE

II. Interruption of Transmission of Aspergillus SPP. Spores

A. Planning New Specialized-Care Units for High-Risk Patients

    1. When constructing new specialized-care units for high-risk 
patients, ensure that patient rooms have adequate capacity to minimize 
fungal spore counts via maintenance of (a) high-efficiency air 
filtration, (b) directed room airflow, (c) positive air pressure in 
patient's room in relation to the corridor, (d) properly sealed room, 
and (e) high rates of room-air changes.424,479-481,484,488,660,661
CATEGORY IB
a. Air Filtration
    Install high efficiency particulate air (HEPA) filters that are 
99.97% efficient in filtering 0.3u-sized particles, at the point of 
use, i.e. at the room-air intake site.424,479-481,484,488,660,661
CATEGORY IB
b. Directed Room Airflow
    Place air-intake and exhaust ports such that room air comes in from 
one side of the room, flows across the patient's bed, and exits on the 
opposite side of the room. In addition, place intake and exhaust ports 
such that healthcare personnel entering the room to care for the 
patient would stand between the patient and the exhaust 
port.480,481
CATEGORY IB
c. Well-Sealed Room
    Construct windows, doors, and intake and exhaust ports to achieve 
complete sealing of the room against air leaks.480,481
CATEGORY IB
d. Room-Air Pressure
    Ensure that room-air pressure can be maintained continuously above 
that of corridor, e.g., as can be demonstrated by performance of the 
smoke-tube test, unless there are clinical-care or infection-control 
contraindications to do so.480,481
CATEGORY IB
    (1) To maintain positive room-air pressure in relation to the 
corridor, supply room air at a rate that is 10-20% more than the rate 
of exhausting air from the room.480,481
CATEGORY IB
    (2) Construct rooms that have an anteroom with an independent 
exhaust for placement of patients at high risk of aspergillosis who 
also have an infection (e.g., varicella or infectious tuberculosis) 
requiring negative room-air pressure in relation to the 
corridor.480
CATEGORY IB
e. Room-Air Changes
    Maintain room-air changes at 15 per 
hour.480,486,487
CATEGORY II
    2. NO RECOMMENDATION for the preferential installation of a 
particular system, such as one with ultra-high (100-400 per hour) air 
change rates, e.g., laminar airflow, over other systems that meet the 
conditions in II-A-1-a through II-A-1-e above.424,479-
481,484,488,660,661
UNRESOLVED ISSUE
    3. Formulate hospital policies to minimize exposures of high-risk 
patients to potential sources of Aspergillus spp., such as hospital 
construction and renovation, cleaning activities, carpets, food, potted 
plants, and flower arrangements.418,437,662-664
CATEGORY IB
    4. NO RECOMMENDATION for prophylactic use of copper-8-quinolinolate 
biocide in fireproofing material.418,427,481,488
UNRESOLVED ISSUE

B. In Existing Facilities With No Cases of Nosocomial Aspergillosis

    1. Place high-risk patients in protected environment that meets the 
conditions outlined in Section II-A-1-a through II-A-1-e 
above.424,437,479,488,660,661,665
CATEGORY IB
    2. Routinely inspect air-handling systems in high-risk patient-care 
areas, maintain adequate air exchanges and pressure differentials, and 
eliminate air leakages. Coordinate repairs of the system with 
relocation of high-risk patients to other areas with optimal air-
handling capabilities.418,428,437
CATEGORY IB
    3. Minimize the time high-risk patients spend outside their rooms 
for diagnostic procedures and other activities; and when high-risk 
patients leave their rooms, require them to wear well-fitting masks 
capable of filtering Aspergillus spp. spores.
CATEGORY IB
    4. Regularly clean ceiling tiles, air-duct grates, and other 
surfaces in patient rooms to prevent dust accumulation, and maintain 
adequate seals on windows to prevent room infiltration by outside air, 
especially in areas occupied by patients at high-risk for developing 
aspergillosis. Conduct such cleaning when the rooms are not occupied by 
patients.437
CATEGORY IB
    5. Systematically review and coordinate infection-control 
strategies with personnel in charge of hospital engineering, 
maintenance, central supply and distribution, and catering.418,473
CATEGORY IB
    6. When planning hospital construction and renovation activities, 
assess whether patients at high-risk for aspergillosis are likely to be 
exposed to high ambient-air spore counts of Aspergillus spp. from 
construction and renovation sites, and develop a plan to prevent such 
exposures.418,473
CATEGORY IB
    7. During construction or renovation activities:
    (a) Construct barriers between patient-care and construction areas 
to prevent dust from entering patient-care areas; these barriers (e.g., 
plastic or drywall) should be impermeable to Aspergillus 
spp.418,428,472,473
CATEGORY IB
    (b) In construction/renovation areas inside the hospital, create 
and maintain negative pressure relative to that in adjacent patient-
care areas if there are no contraindications for such pressure 
differential, e.g., there are patients with infectious tuberculosis in 
the adjacent patient-care areas.418,428,472,473,488
CATEGORY II
    (c) Direct pedestrian traffic from construction areas away from 
patient-care areas to limit opening and closing of doors (or other 
barriers) that may cause dust dispersion, entry of contaminated air, or 
tracking of dust into patient areas.418,428,472,473
CATEGORY IB
    (d) Clean newly constructed areas before allowing patients to enter 
the areas.418,473
CATEGORY IB
    8. Eliminate exposures of patients at high-risk for aspergillosis 
to activities, such as floor or carpet vacuuming, that may cause spores 
of Aspergillus spp. and other fungi to be aerosolized.418,437,473
CATEGORY IB
    9. Eliminate exposures of patients at high-risk for aspergillosis 
to potential environmental sources of Aspergillus spp., such as 
Aspergillus-contaminated food, potted plants, or flower 
arrangements.418,437,473,662-664
CATEGORY II
    10. Prevent birds from gaining access to hospital air-intake 
ducts.474
CATEGORY IB

C. When a Case of Nosocomial Aspergillosis Occurs

    1. Begin a prospective search for additional cases in hospitalized 
patients and an intensified retrospective review of the hospital's 
microbiologic, histopathologic, and postmortem records.
CATEGORY IB
    2. If there is no evidence of continuing transmission, continue 
routine maintenance procedures to prevent nosocomial aspergillosis, as 
in Section II-B-1 through II-B-10 above.
CATEGORY IB
    3. If evidence of continuing Aspergillus spp. infection exists, 
conduct an environmental investigation to determine and eliminate the 
source.424,427,428,472,484,488
CATEGORY IB
    a. Collect environmental samples from potential sources of 
Aspergillus spp., especially those sources implicated in the 
epidemiologic investigation, by using appropriate 
methods,424,427,428,472,484,488,666 e.g., use of a high-volume air 
sampler rather than settle plates.424
CATEGORY IB
    b. Perform molecular subtyping of Aspergillus spp. obtained from 
patients and the environment to establish strain identity.476,477
CATEGORY IB
    c. If air-handling systems supplying high-risk patient-care areas 
are not optimal, consider temporary deployment of portable HEPA filters 
until rooms with optimal air-handling systems are available for all 
patients at high risk of invasive aspergillosis.469
CATEGORY II
    d. If an environmental source is identified, perform corrective 
measures as needed to eliminate the source from the high-risk patients' 
environment.
CATEGORY IB
    e. If an environmental source is not identified, review existing 
infection-control measures, including engineering aspects, to identify 
potential areas that can be corrected or improved.
CATEGORY IB

III. Modifying Host Risk for Infection

    A. Administer cytokines, including granulocyte colony-stimulating 
factor and granulocyte-macrophage stimulating factor, to increase host 
resistance to aspergillosis by decreasing the duration and severity of 
chemotherapy-induced granulocytopenia.464,465
CATEGORY II
    B. NO RECOMMENDATION for administration of intranasal amphotericin 
B or oral antifungal agents (including amphotericin B and triazole 
compounds) in high-risk patients for prophylaxis against 
aspergillosis.466,467,667
UNRESOLVED ISSUE

Prevention and Control of Respiratory Syncytial Virus Infection

    (The principles and recommendations below are applicable for 
prevention and control of nosocomial lower respiratory tract infections 
due to adenovirus, parainfluenza virus and rhinovirus.)

I. Staff Education and Infection Surveillance

A. Staff Education

    Educate personnel about the epidemiology, modes of transmission and 
means of preventing spread of respiratory syncytial virus 
(RSV).215,611-613
CATEGORY IA

B. Surveillance

    1. Establish mechanism(s) by which the appropriate hospital 
personnel are promptly alerted to any increase in RSV activity in the 
local community.
CATEGORY IB
    2. During periods of increased prevalence of RSV in the community 
(and during December-March), attempt prompt diagnosis of RSV infection 
by using rapid diagnostic techniques as clinically indicated in 
pediatric patients, especially infants, and in immunocompromised adults 
admitted to the hospital with respiratory illness.545,549
CATEGORY IB

II. Interruption of Transmission of RSV

A. Prevention of Person-to-Person Transmission

1. Primary Measures for Contact Isolation
    a. Handwashing. Wash hands after contact with a patient, or after 
touching respiratory secretions or fomites potentially contaminated 
with respiratory secretions, whether or not gloves are 
worn.207,503,524-526,547
CATEGORY IA
    b. Gloving. (1) Wear gloves for handling patients or respiratory 
secretions of patients with proven or suspected RSV infection, or 
fomites potentially contaminated with patient 
secretions.215,503,524,525,543,549
CATEGORY IA
    (2) Change gloves between patients, or after handling respiratory 
secretions or fomites contaminated with secretions from one patient 
before contact with another patient.215,217 Wash hands after 
removing gloves. (See II-A-1-a, above.)
CATEGORY IA
    c. Gowning. Wear a gown when soiling with respiratory secretions 
from a patient is anticipated, e.g., when handling infants with RSV 
infection or other viral respiratory illness, and change the gown after 
such contact and before caring for another patient.215,542,544,549
CATEGORY IB
    d. Staffing. Restrict healthcare workers in the acute stages of an 
upper respiratory illness, i.e., those who are sneezing and/or 
coughing, from taking care of RSV-uninfected infants and other patients 
at high risk for complications from RSV infection, e.g., children with 
severe underlying cardio-pulmonary conditions, children receiving 
chemotherapy for malignancy, and patients who are otherwise 
immunocompromised.547,549
CATEGORY IB
    e. Limiting Visitors. Do not allow persons with symptoms of 
respiratory infection to visit uninfected pediatric, immunosuppressed, 
and cardiac patients.543
CATEGORY II
2. Control of RSV Outbreaks
a. Use of Private Room, Cohorting, and Patient-Screening
    To control ongoing RSV transmission in the hospital, admit young 
children with symptoms of viral respiratory illness to single rooms 
when possible, OR perform RSV-screening diagnostic tests on young 
children upon admission and cohort them according to their RSV-
infection status.543,545,547,549
CATEGORY II
b. Personnel Cohorting
    During an outbreak of nosocomial RSV, cohort personnel as much as 
practical, i.e., restrict personnel who give care to infected patients 
from giving care to uninfected patients, and vice-
versa.543,547,549
CATEGORY II
c. Postponing Patient Admission
    During outbreaks of nosocomial RSV, postpone elective admission of 
uninfected patients at high risk of complications from RSV infection.
CATEGORY II
d. Wearing Eye-Nose Goggles
    NO RECOMMENDATION for wearing eye-nose goggles for close contact 
with an RSV-infected patient.546,550
UNRESOLVED ISSUE

Prevention and Control of Influenza

I. Staff Education and Infection Surveillance

A. Staff Education

    Educate personnel about the epidemiology, modes of transmission and 
means of preventing the spread of influenza.611-613,668,669
CATEGORY IA

B. Surveillance

    1. Establish mechanism(s) by which the appropriate hospital 
personnel are promptly alerted of any increase in influenza activity in 
the local community.
CATEGORY IB
    2. Arrange for laboratory tests to be available to clinicians, for 
use when clinically indicated, to promptly confirm the diagnosis of 
influenza and other acute viral respiratory illnesses, especially 
during November-April.573-578
CATEGORY IB

II. Modifying Host Risk to Infection

A. Vaccination

1. Patients
    Offer vaccine to outpatients and inpatients at high risk of 
complications from influenza, beginning in September and continuing 
until influenza activity has begun to decline.581,584,603,670-672 
Patients at high risk of complications from influenza include those 
65 years of age; in long-term-care units; with chronic 
disorders of the pulmonary or cardiovascular systems, diabetes 
mellitus, renal dysfunction, hemoglobinopathies, musculo-skeletal 
disorders that impede adequate respiration, or immunosuppression; and 
children 6 months-18 years of age who are receiving long-term aspirin 
therapy.581
CATEGORY IA
2. Personnel
    Vaccinate healthcare workers before the influenza season each year, 
preferably between mid-October and mid-November. Until influenza 
activity declines, continue to make vaccine available to newly hired 
personnel and to those who initially refuse vaccination. If vaccine 
supply is limited, give highest priority to staff caring for patients 
at greatest risk of severe complications from influenza infection, as 
listed in Section II-A-1 above.581
CATEGORY IB

B. Use of Antiviral Agents (See Section IV Below, Control of Influenza 
Outbreaks)

III. Interruption of (Person-to-Person) Transmission

    A. Keep a patient for whom influenza is suspected or diagnosed in a 
private room, or in a room with other patients with proven influenza, 
unless there are medical contraindications to do so.
CATEGORY IB
    B. As much as feasible, maintain negative air pressure in rooms of 
patients for whom influenza is suspected or diagnosed, or place 
together persons with influenza-like illness in a hospital area with an 
independent air-supply-and-exhaust system.566,567,569,673
CATEGORY II
    C. Institute masking of individuals who enter the room of a patient 
with influenza.566,567,673
CATEGORY IB
    D. As much as possible during periods of influenza activity in the 
community, remove patient-care staff who have symptoms of febrile upper 
respiratory tract infection suggestive of influenza from duties that 
involve direct patient contact.604,674
CATEGORY II
    E. When community and/or nosocomial outbreaks are characterized by 
high attack rates and severe illness:
    1. Restrict hospital visitors who have a febrile respiratory 
illness.
CATEGORY IB
    2. Curtail or eliminate elective medical and surgical admissions as 
necessary.
CATEGORY IB
    3. Restrict cardiovascular and pulmonary surgery to only emergency 
cases.
CATEGORY IB

IV. Control of Influenza Outbreaks

A. Determining the Outbreak Strain

    Early in the outbreak, obtain nasopharyngeal-swab or nasal-wash 
specimens from patients with symptoms suggestive of influenza for 
influenza virus culture or antigen detection.
CATEGORY IB

B. Vaccination of Patients and Personnel

    Administer current influenza vaccine to unvaccinated patients and 
staff, especially if the outbreak occurs early in the influenza 
season.562,581
CATEGORY IB

C. Amantadine or Rimantadine Administration

    1. When a nosocomial outbreak of influenza A is suspected or 
recognized:
    a. Administer amantadine or rimantadine for prophylaxis to all 
uninfected patients in the involved unit for whom it is not 
contraindicated. Do not delay administration of amantadine or 
rimantadine unless the results of diagnostic tests to identify the 
infecting strain(s) can be obtained within 12 to 24 hours after 
specimen collection.584,587
CATEGORY IB
    b. Administer amantadine or rimantadine for prophylaxis to 
unvaccinated staff members for whom it is not medically 
contraindicated, and who are in the involved unit or taking care of 
high-risk patients.584
CATEGORY II
    2. Discontinue amantadine or rimantadine if laboratory tests 
confirm or strongly suggest that influenza type A is not the cause of 
the outbreak.585,602
CATEGORY IA
    3. If the cause of the outbreak is confirmed or believed to be 
influenza type A AND vaccine has been administered only recently to 
susceptible patients and personnel, continue amantadine or rimantadine 
prophylaxis until 2 weeks after the vaccination.675
CATEGORY IB
    4. To the extent possible, do not allow contact between those at 
high risk of complications from influenza and patients or staff who are 
taking amantadine or rimantadine for treatment of acute respiratory 
illness; prevent contact during and for two days after the latter 
discontinue treatment.586,598-602
CATEGORY IB

D. Interruption of (Person-to-Person) Transmission (See Section III, A-
E Above.)

  Table 1.--Microorganisms Isolated From Respiratory Tract Specimens Obtained by Various Representative Methods 
                          From Adult Patients With a Diagnosis of Nosocomial Pneumonia                          
----------------------------------------------------------------------------------------------------------------
                              Schaber\4\           Bartlett\5\           Fagon\6\               Torres\7\       
----------------------------------------------------------------------------------------------------------------
Hospital Type...........  NNIS & UMHA........  Veterans...........  General............  General.               
Patients Studied:                                                                                               
  Ventilated or Non-      Mixed..............  Mixed..............  Ventilated.........  Ventilated.            
   ventilated.                                                                                                  
  Number................  N/AB...............  159................  49.................  78.                    
Number of episodes of     N/A................  159................  52.................  78.                    
 pneumonia.                                                                                                     
Specimen(s) Cultured....  Sputum, Tracheal     Transtracheal        Protected Specimen   Protected Specimen     
                           Aspirate.            Aspirate, Pleural    Brushing.            Brushing, Lung        
                                                Fluid, Blood.                             Aspirate, Pleural     
                                                                                          Fluid, Blood.         
Culture Results:                                                                                                
  No organism isolated..  N/A................  0..................  0..................  54%C.                  
  Polymicrobial.........  N/A................  54%C...............  40%C...............  13%C.                  
  Number of isolates....  15,499.............  314................  111................  N/A.                   
                                                                                                                
    Aerobic Bacteria                                                                                            
                                                                                                                
  Gram-Negative Bacilli.  50%D...............  46%E...............  75%E...............  16%F.                  
  Pseudomonas aeruginosa  17%D...............  9%E................  31%E...............  5%F.                   
  Enterobacter sp.......  11.................  4..................  2..................  0.                     
  Klebsiella sp.........  7..................  23.................  4..................  0.                     
  E. coli...............  6..................  14.................  8..................  0.                     
  Serratia sp...........  5..................  0..................  0..................  1.                     
  Proteus sp............  3..................  11.................  15.................  1.                     
  Citrobacter sp........  1..................  0..................  2..................  0.                     
  Acinetobacter           N/A................  0..................  15.................  9.                     
   calcoaceticus.                                                                                               
  Others................  N/A................  0..................  10.................  0.                     
Haemophilus influenza...  6%D................  17%E...............  10%E...............  0%F.                   
  Legionella sp.........  N/A................  N/A................  2%E................  2%F.                   
Gram-Positive Cocci.....  17%D...............  56%E...............  52%E...............  4%F.                   
  Staphylococcus aureus.  16%D...............  25%E...............  33%E...............  2%F.                   
  Streptococcus sp......  1..................  31.................  21.................  2.                     
  Others................  0..................  0..................  8..................  0.                     
Anaerobes...............  N/A................  35%E...............  2%E................  0.                     
  Peptostreptococcus....  N/A................  14%E...............  N/A................  0.                     
  Fusobacterium sp......  N/A................  10.................  N/A................  0.                     
  Peptococcus sp........  N/A................  11.................  N/A................  0.                     
  Bacteroides             N/A................  9..................  N/A................  0.                     
   melaninogenicus.                                                                                             
  Bacteroides fragilis..  N/A................  8..................  N/A................  0.                     
Fungi...................  4%D................  N/A................  0..................  1%F.                   
  Aspergillus sp........  N/A................  N/A................  0..................  1%F.                   
  Candida sp............  4%D................  N/A................  0..................  0.                     
Viruses.................  N/A................  N/A................  N/A................  N/A.                   
----------------------------------------------------------------------------------------------------------------
Legend:                                                                                                         
                                                                                                                
ANNIS & UMH=National Nosocomial infection Surveillance System and University of Michigan Hospital.              
BN/A=Not Applicable: Not tested or Not reported.                                                                
CPercent episodes.                                                                                              
DPercent isolates.                                                                                              
EPercent episodes (Percentages not additive due to polymicrobial etiology in some episodes).                    
FPercent patients with pure culture.                                                                            
                                                                                                                
 Note: Footnotes appear at the end of the document.                                                             


         Table 2--Controlled Studies on Nosocomial Lower Respiratory Tract Infections and Other Associated Outcomes of Selective Decontamination of the Digestive Tract in Adult Patients With Mechanically Assisted Ventilation        
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                            Lower respiratory tract infection                   Colonization or infection with       Overall mortality in hospital     Mean total number of days in ICUB
                                                           ------------------------------------------------------------------      resistantA microorganisms     -----------------------------------------------------------------------
           Author                    Study patients                                                 Infection rate           ------------------------------------                                                                       
                                                                  Diagnostic method      ------------------------------------                                         SDDC (%)        Controls (%)          SDDC            Controls    
                                                                                              SDDC (%)        Controls (%)        SDDC (%)        Controls (%)                                                                          
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Stoutenbeek147 (1984).......  Trauma SDD=63; Controls=59..  Clinical & Radiologic;D TSE   8...............  59..............  ``No increase''.  ``No increase''.  3...............  8...............  Not reported....  Not reported.   
                                                             culture.                                                                                                                                                                   
Unertl148 (1987)............  General ICU SDD=19;           Clinical & Radiologic;D.....  21..............  70..............  21F.............  20F.............  26..............  30..............  18G.............  23G.            
                               Controls=20.                                                                                                                                                                                             
Ledingham149 (1988).........  General ICU SDD=163;          Clinical & Radiologic;D.....  2...............  11..............  ``No increase''.  ``No increase''.  24..............  24..............  Not reported....  Not reported.   
                               Controls=161.                                                                                                                                                                                            
Kerver150 (1988)............  Surgical ICU SDD=49;          Clinical & RadiologicD......  12..............  85..............  ``Not recorded''  ``Not recorded''  29..............  32..............  17..............  20              
                               Controls=47.                                                                                                                       IRH=4...........  IRH=17..........                                    
Ulrich151 (1989)............  General ICU SDD=48;           Clinical & Radiologic;D TSE   15..............  50..............  GP=78I..........  GP=44I..........  31..............  54..............  17..............  13.             
                               Controls=52.                  culture.                                                         GN=3J...........  GN=2J...........  IRH=0...........  IRH=15..........                                    
Brun-Buisson152 (1989)......  Medical ICU SDD=36;           Clinical & Radiologic;D TSE   20..............  22..............  3F..............  16F.............  22..............  24..............  14..............  15.             
                               Controls=50.                  PSBK culture.                                                                                        IRH=9...........  IRH=10..........                                    
Godard153 (1990)............  General ICU SDD=97;           Clinical & Radiologic;D TSE   2...............  15..............  GN=15I..........  GN=15I..........  12..............  18..............  11..............  16.             
                               Controls=84.                  & PSBK culture.                                                                                                                                                            
Rodriquez-Roldan154 (1990)..  General ICU SDD=13;           Clinical & Radiologic;D TSE   Pn-0L...........  Pn=73L..........  ``None noticed''  ``None noticed''  30..............  33..............  Not reported....  Not reported.   
                               Controls=15.                  culture.                     TB=23M..........  TB=20M..........                                      IRH=0...........  IRH=13..........                                    
Flaherty155 (1990)..........  Cardiac Surgery ICU SDD=51;   Clinical & Radiologic;D.....  2...............  9...............  GN=22N..........  GN=21N..........  0...............  2...............  Not reported....  Not reported.   
                               Controls=56.                                                                                                                                                                                             
McClelland156 (1990)........  Renal & Respiratory Failure   TSE culture.................  7...............  50..............  Not reported....  ``Not reported''  60..............  58..............  Not reported....  Not reported.   
                               SDD=15; Controls=12.                                                                                                               IRH=27..........  IRH=8...........                                    
Tetteroo157 (1990)..........  Esophageal Resection SDD=56;  Clinical & Radiologic;D       2...............  14..............  2F..............  4F..............  5...............  4...............  6...............  5.              
                               Controls=56.                  Culture of Bronchial                                                                                 IRH=4...........  irH=0...........                                    
                                                             Aspirate.                                                                                                                                                                  
Pugin158 (1991).............  Surgical ICU SDD=25;          Clinical & Radiologic;D TSE   16..............  78..............  ``No New          ``No New          28..............  26..............  13..............  15.             
                               Controls=27.                  culture.                                                          antibiotic        antibiotic                                                                             
                                                                                                                               resistance''.     resistance''.                                                                          
Aerdts159 (1991)............  General ICU SDD=17; Controls- Clinical & Radiologic;D TSE   6...............  A=78............  ``Not observed''  ``Not observed''  12..............  A=22............  23..............  A=30            
                               A=18N Controls-B=21O.         culture.                                       B=62............                                      IRH=6...........  IRH=11..........                    B=25.           
                                                                                                                                                                                    B=10............                                    
                                                                                                                                                                                    IRH=0...........                                    
Hartenauer160 (1991)........  Surgical ICU ICU-1: SDD=50;   Clinical & Radiologic;D TSE   ICU-1; 10.......  46..............  S=34Q...........  S=33Q...........  38..............  48..............  12..............  13.             
                               Controls=61 ICU-2: SDD=49     culture.                     ICU-2: 10.......  45..............  GN=0N...........  GN=0N...........  IRH=8...........  IRH=21..........  13..............  17.             
                               Controls=40.                                                                                   S=37Q...........  S=37Q...........  31..............  43..............                                    
                                                                                                                              GN=0N...........  GN=0N...........  IRH=6...........  IRH=25..........                                    
Fox161 (1991)...............  Cardiac Bypass SDD=12;        TSE culture.................  66..............  50..............  Not reported....  Not reported....  17..............  66..............  12..............  12.             
                               Controls=12.                                                                                                                                                                                             
Blair162 (1991).............  General ICU SDD=126;          Clinical & Radiologic;D.....  10..............  35..............  ``No evidence of  ``No evidence of  14..............  19..............  8...............  8.              
                               Controls=130.                                                                                   increased         increased                                                                              
                                                                                                                               resistance''.     resistance''.                                                                          
Vandenbroucke-Grauls163       ICUs (Pooled data)R SDD-      Clinical & Radiologic;D TSE   A=7.............  A=28............  ``No increase in  ``No increase in  A=25............  A=26............  Not reported....  Not reported.   
 (1991).                       A=488; Controls-A             culture.                     B=8.............  B=45............   resistant         resistant        B=21............  B=26............                                    
                               (Historical)=540 SDD-B=225;                                                                     microorganisms    microorganisms                                                                         
                               Control-B (Random)=266.                                                                         in 10 of 11       in 10 of 11                                                                            
                                                                                                                               studies''.        studies''.                                                                             
Winter164 (1992)............  General ICU SDD=91; Control-  Clinical & Radiologic;D BALS  3...............  A=11............  1-8T............  A=1-7T..........  36..............  A=43............  6...............  A=7.            
                               A=84; Controls-B=92.          culture.                                       B=23............                    B=1-17T.........                    B=43............                    B=8.            
Ferrer165 (1992)............  General ICU SDD+22;           Clinical & Radiologic;D TSE   27..............  32..............  Not reportedU...  Not reportedU...  32..............  23..............  18..............  15.             
                               Controls=22.                  Culture.                                                                                                                                                                   
Hammond166 (1992)...........  General ICU SDD=114;          Clinical & Radiologic;D TSE   Pn=15L..........  Pn=15L..........  Not reportedV...  Not reportedV...  18..............  17..............  16..............  17.             
                               Controls=125.                 culture.                     Br=6W...........  Br=6W...........                                      IRH=6...........  IRH=6...........                                    
Gastinne167 (1992)..........  Medical ICU SDD=220;          Clinical & Radiologic;D TSE   12..............  15..............  Not reported....  Not reported....  40..............  36..............  18..............  19.             
                               Controls=225.                  PSBK culture.                                                                           34X.............  34X.............                                    
Cockerill168 (1992).........  Surgical and Medical ICUs     Clinical & Radiologic;D       Pn=5L...........  Pn=16L..........  16..............  11..............  15..............  21..............  10..............  12.             
                               SDD=75; Controls=75.          TSE culture.     TB=4M...........  TB=5M...........                                                                                                            
Korinek169 (1993)...........  Neurosurgical ICU SDD=63;     Clinical & Radiologic;D TSE   24..............  42..............  ``No evidence of  ``No evidence of  8...............  7...............  24..............  29.             
                               Controls=60.                  & PSBK culture.                                                   increased         increased                                                                              
                                                                                                                               resistance''.     resistance''.                                                                          
SDD Trialists170 (1993).....  ICUs (Pooled Data)R           Variable....................  Odds Ratio=       Odds Ratio=       Not analyzed....  Not analyzed....  27..............  27..............  Not analyzed....  Not analyzed.   
                               SDD=2047; Controls=2095.                                   0.37;Y 95%        0.37;Y 95%                                            Odds Ratio=0.90;  Odds Ratio=0.90;                                    
                                                                                           CIZ.0.31-0.43.    CIZ.0.31-0.43.                                       95% CIZ:0.79-104  95% CIZ:0.79-104                                    
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Legend:                                                                                                                                                                                                                                 
                                                                                                                                                                                                                                        
AResistant to at least one antimicrobial in the SDD regimen, during the study period.                                                                                                                                                   
BICU: Intensive care unit.                                                                                                                                                                                                              
CSDD: Selective digestive tract decontamination.                                                                                                                                                                                        
DClinical criteria included temperature >38 deg.C, purulent bronchorrhea, WBC >(12,000-15,000/mm3) Radiologic criterion was evidence of new and progressive infiltrate(s).                                                              
ETS: Tracheal secretions.                                                                                                                                                                                                               
FPercentage of patients infected or colonized with gram-positive (GP) and/or gram-negative bacillary (GN) organisms at any body site.                                                                                                   
GMedian.                                                                                                                                                                                                                                
HIR: Infection-related.                                                                                                                                                                                                                 
IPercentage of gram-positive (GP) isolates.                                                                                                                                                                                             
JPercentage of gram-negative bacillary (GN) isolates.                                                                                                                                                                                   
KPSB: Protected-specimen brushing.                                                                                                                                                                                                      
LPn: Pneumonia.                                                                                                                                                                                                                         
MTB: Tracheo-bronchial infection.                                                                                                                                                                                                       
NPercentage of patients with GN infection or colonization.                                                                                                                                                                              
OPatients given penicillin (ampicillin, piperacillin or flucloxacillin) for clinical infection(s).                                                                                                                                      
PPatients given cephalosporin (cephadrine, cefuroxime, or cefotaxime) for clinical infection(s).                                                                                                                                        
QPercentage of patients with coagulase-negative staphylococcal infection or colonization.                                                                                                                                               
RMeta-analysis.                                                                                                                                                                                                                         
SBAL: Broncho-alveolar lavage.                                                                                                                                                                                                          
TPercentage of isolates.                                                                                                                                                                                                                
UHowever, MRSA bronchial colonization occurred in 45% of SDD patients and 21% of controls.                                                                                                                                              
VHowever, at 4 weeks, 13% and 5%, respectively, of oropharyngeal cultures of SDD and control patients had MRSA, and 41% of SDD and control patients were colonized with enterococci.                                                    
WBr: Bronchial infraction.                                                                                                                                                                                                              
XIn ICU.                                                                                                                                                                                                                                
YComputed using data from 3,836 patients and 526 events, 260 in SDD- and 366 in control-patients.                                                                                                                                       
ZCI: Confidence interval.                                                                                                                                                                                                               
                                                                                                                                                                                                                                        
Note: Footnotes appear at the end of the document.                                                                                                                                                                                      


     Table 3.--Risk Factors and Suggested Infection Control Measures for Prevention of Nosocomial Pneumonia     
----------------------------------------------------------------------------------------------------------------
                                                  Infection control measures suggested to prevent nosocomial    
                Risk factors                                              pneumonia                             
----------------------------------------------------------------------------------------------------------------
Bacterial Pneumonia:                                                                                            
  Host-Related                                                                                                  
    Age (>65 years)                                                                                             
    Underlying illness:                                                                                         
      Chronic Obstructive Pulmonary Disease  Good chest physiotherapy: incentive spirometry; positive end       
       (COPD).                                expiratory pressure or continuous positive airway pressure by face
                                              mask.                                                             
      Immunosuppression....................  Avoid exposure to potential nosocomial pathogens; decrease duration
                                              of immunosuppression, such as by administration of granulocyte    
                                              macrophage colony stimulating factor (GMCSF).                     
      Depressed consciousness..............  Caution on prescribing central nervous system depressants.         
      Surgery (thoracic/abdominal).........  Chest physiotherapy if with COPD; proper positioning; early        
                                              ambulation.                                                       
  Device-Related...........................  Proper cleaning, sterilization or disinfection, and handling of    
                                              devices; remove devices as soon as indication for their use       
                                              ceases.                                                           
      Endotracheal intubation and            Gentle suctioning of secretions; place patient in semirecumbent    
       Mechanical ventilation.                position, i.e., 30 deg. head-elevation; use nonalkalinizing       
                                              gastric cytoprotective agent on patients at risk for stress       
                                              bleeding; changing ventilator circuits not more often than every  
                                              48 hours; draining and discarding inspiratory-tubing condensate,  
                                              or using heat-moisture exchanger if indicated.                    
      Nasogastric-tube (NGT) placement and   Use small-bore NGT; routinely verify appropriate tube placement;   
       Enteral feeding.                       promptly remove NGT. Avoid large-bolus feeding; drain residual.   
  Personnel- or Procedure-Related:                                                                              
    Cross-contamination by hands...........  Educate and train personnel; adequate handwashing and appropriate  
                                              gloving; surveillance for cases of pneumonia, and feedback to     
                                              personnel.                                                        
    Antibiotic administration..............  Prudent antibiotic use, especially on high-risk intensive-care unit
                                              (ICU) patients.                                                   
Legionnaires' Disease:                                                                                          
  Host-Related                                                                                                  
    Immunosuppression......................  Decrease duration of immunosuppression, such as by administration  
                                              of GMCSF.                                                         
  Device-Related                                                                                                
    Contaminated aerosol from devices......  Sterilize/disinfect aerosol-producing devices before use; use only 
                                              sterile water for respiratory humidifying devices; not using cool-
                                              mist room-air ``humidifiers''.                                    
  Environment-Related                                                                                           
    Aerosols from contaminated water supply  Hyperchlorinate or superheat hospital water system; routine        
                                              maintenance of water-supply system; consider use of sterile water 
                                              for drinking by immunosuppressed patients.                        
    Cooling-tower draft....................  Proper design, placement, and maintenance of cooling towers.       
Aspergillosis:                                                                                                  
  Host-Related                                                                                                  
    Severe granulocytopenia................  Decrease duration of immunosuppression, such as by administration  
                                              of GMCSF; consider placing severely granulocytopenic patients in  
                                              protected environment.                                            
  Environment-Related                                                                                           
    Construction activity..................  Remove granulocytopenic patients from vicinity of construction; if 
                                              not already done, placing severely granulocytopenic patients in   
                                              protected environment; mask severely granulocytopenic patients    
                                              when they leave protected environment.                            
    Other environmental sources of           Routine maintenance of hospital air-handling system and rooms of   
     aspergilli.                              immunosuppressed patients.                                        
Respiratory Syncytial Virus Infection:                                                                          
  Host-Related                                                                                                  
    Age (<2 years) Congenital pulmonary/     Consider routine pre-admission screening of high-risk patients for 
     cardiac disease, Immunosuppression.      severe RSV infection, followed by cohorting of patients and       
                                              nursing personnel during hospital outbreaks of RSV infection.     
  Personnel- or Procedure-Related                                                                               
    Cross-contamination by hands...........  Personnel education; handwashing; gloving; gowning; during         
                                              outbreaks, use private rooms or cohort patients and nursing       
                                              personnel, and limit visitors.                                    
Influenza:                                                                                                      
                                             Use private room or cohort infected patients.                      
  Host-Related                                                                                                  
    Age (>65 years) Immunosuppression......  Vaccinate high-risk patients before the influenza season each year;
                                              use amantadine or rimantadine for chemoprophylaxis during an      
                                              outbreak.                                                         
  Personnel-Related                                                                                             
    Infected personnel.....................  Vaccinate personnel caring for high-risk patients, before the      
                                              influenza season each year; use amantadine or rimantadine for     
                                              prophylaxis during an outbreak.                                   
----------------------------------------------------------------------------------------------------------------

BILLING CODE 4160-18-P

TN02FE94.004

BILLING CODE 4160-18-C

Appendix A--Semicritical Items Used on the Respiratory Tract

Air-pressure monitors
Anesthesia breathing circuits including:
    inspiratory and expiratory tubings
    y connectors
    right-angle connectors
    face mask
    reservoir bags
Breathing circuits of mechanical ventilators
Bronchoscopes and their accessories
CO2 analyzers
Endotracheal and endobronchial tubes
Laryngoscope blades
Mouthpieces and tubings of pulmonary-function testing equipment
Oral and nasal airways
Resuscitation bags
Spirometers
Suction catheters

Appendix B--Maintenance Procedures to Decrease Survival and 
Multiplication of Legionella SPP. In Potable-Water Distribution Systems

I. Providing water at 50 deg.C at all points in the heated 
water system, including the taps

    This requires that water in calorifiers (water heaters) be 
maintained at 60 deg.C. In the United Kingdom, where 
maintenance of water temperatures at 50 deg.C in hospitals 
has been mandated, installation of blending or mixing valves at or near 
taps to reduce the water temperature to 43 deg.C has been 
recommended in certain settings to reduce the risk of scald injury to 
patients, visitors, and health care workers.400 However, 
Legionella spp. can multiply even in short segments of pipe containing 
water at this temperature. Increasing the flow rate from the hot-water-
circulation system may help lessen the likelihood of water stagnation 
and cooling.403,676 Insulation of plumbing to ensure delivery of 
cold (<20 deg.C) water to water heaters (and to cold-water outlets) may 
diminish the opportunity for bacterial multiplication.\345\ ``Dead 
legs'' or capped spurs within the plumbing system provide areas of 
stagnation and cooling to <50 deg.C regardless of the circulating-water 
temperature; these segments may need to be removed to prevent 
colonization.677 Rubber fittings within plumbing systems have been 
associated with persistent colonization, and replacement of these 
fittings may be required for Legionella spp. eradication.678

II. Continuous chlorination that maintains concentrations of free 
residual chlorine at 1-2 mg/L at the tap

    This requires flow-adjusted, continuous injectors of chlorine 
throughout the water distribution system. Adverse effects of continuous 
chlorination include accelerated corrosion of plumbing resulting in 
system leaks and production of potentially carcinogenic 
trihalomethanes. However, when levels of free residual chlorine are 
below 3 mg/L, trihalomethane levels are kept below the maximum ``safety 
level'' recommended by the Environmental Protection 
Agency.401,679,680

Appendix C--Culturing Environmental Specimens for Legionella SPP

I. Recommended procedure for collecting and processing environmental 
specimens for Legionella spp.

    A. Collect water (if possible, one-liter samples) in sterile, 
screw-top bottles, preferably containing sodium thiosulfate at a 
concentration of 0.5 cc of 0.1N solution/liter of sample water. (Sodium 
thiosulfate inactivates any residual halogen biocide).
    B. Collect culture-swabs of the internal surfaces of faucets, 
aerators, and showerheads; in a sterile, screw-top container such as a 
50 cc plastic centrifuge tube, submerge each swab in 5-10 cc of sample 
water taken from the same device from which the sample was obtained.
    C. As soon as possible after collection, water samples and swabs 
should be transported to and processed in a laboratory proficient at 
culturing water specimens for Legionella spp. Samples may be 
transported at room temperature but must be protected from temperature 
extremes.
    D. Test samples for the presence of Legionella spp. by culture onto 
semi-selective media. Use standard laboratory procedures. (Detection of 
Legionella spp. antigen by the direct fluorescent antibody technique is 
not suitable for environmental samples.681-683 In addition, the 
use of polymerase chain reaction (PCR) for identification of Legionella 
spp. is not recommended until more data on the sensitivity and 
specificity of this procedure are available.684)

II. Possible samples and sampling sites for Legionella spp. in the 
hospital
Water Samples
Potable Water System
    Incoming water main
    Water softener
    Holding tanks/cisterns
    Water heater tanks (inflow and outflow sites)
    Potable water outlets (faucets or taps, showers) especially outlets 
located in or near case-patients' rooms
Cooling Tower/Evaporative Condenser
    Make-up water (water added to system to replace water lost by 
evaporation, drift, and leakage)
    Basin (area under tower for collection of cooled water)
    Sump (section of basin from which cooled water returns to heat 
source)
    Heat source (e.g., chillers)
Other Sources
    Humidifiers
    Bubblers for oxygen
    Water used for respiratory therapy equipment
    Decorative fountains
    Irrigation equipment
    Fire sprinkler system (if recently used)
    Whirlpools/spas
Swabs
Potable Water System
    Faucets (proximal to aerators)
    Faucet aerators
    Shower heads
Cooling Towers
    Internal components (e.g., splash bars and other fill surfaces)
    Areas with visible biofilm accumulation

Appendix D--Procedure for Cleaning Cooling Towers and Related Equipment

(Adapted from the Emergency Protocol in Control of Legionella spp. in 
Cooling Towers: Summary Guidelines.415)
I. Preparatory to Chemical Disinfection and Mechanical Cleaning
A. Provide protective equipment to workers who would perform the 
disinfection, to prevent their exposure to a) chemicals used for 
disinfection, and b) aerosolized water containing Legionella spp. 
Protective equipment may include full-length protective clothing, 
boots, gloves, goggles, and a full- or half-face mask that combines 
high efficiency particulate air filter and chemical cartridges to 
protect against airborne chlorine levels of up to 10 mg/L.
B. Shut off cooling-tower.
    1. If possible, shut off heat source.
    2. Shut off fans, if present, on the cooling tower/evaporative 
condenser (CT/EC).
    3. Shut off the system blowdown (purge) valve. Shut off automated 
blowdown controller, if present, and set system controller to manual.
    4. Keep make-up water valves open.
    5. Close building air-intake vents within at least 30 meters of the 
CT/EC until after the cleaning procedure is complete.
    6. Continue operating pumps for water circulation through the CT/
EC.
II. Chemical Disinfection
A. Add fast-release, chlorine-containing disinfectant in pellet, 
granular, or liquid form, and follow instructions on the product label. 
Examples of disinfectants are sodium hypochlorite (NaOCl) or calcium 
hypochlorite (Ca(OCl)2, calculated to achieve initial FRC of 50 
mg/L, i.e., 3.0 lbs (1.4 kg) industrial grade NaOCl (12-15% available 
Cl) per 1,000 gallons of CT/EC water; 10.5 lbs (4.8 kg) domestic grade 
NaOCl (3-5% available Cl) per 1,000 gallons of CT/EC water; or 0.6 lb 
(0.3 kg) Ca(OCl)2 per 1,000 gallons of CT/EC water. (Other 
appropriate compounds may be suggested by a water-treatment 
specialist.) If significant biodeposits are present, add more chlorine. 
If the water volume in CT/EC is unknown, estimate it (in gallons) to be 
10x the recirculation rate in gallons/minute or 30x the refrigeration 
capacity in tons.
B. Record type and quality of all chemicals used for disinfection, 
exact time when chemicals are added to the system, and time and results 
of measurements of free residual chlorine (FRC) and pH.
C. Within 15 minutes of adding disinfectant, add the dispersant by 
first dissolving it in water and adding the resulting solution to a 
turbulent zone in the water system. Examples of low or non-foaming, 
silicate-based dispersants are: automatic-dishwasher compounds, such as 
Cascade* or Calgonite* or an equivalent product. (Dispersants are added 
at 10-25 lbs. (4.5-11.25 kg) per 1,000 gallons of CT/EC water.)

    *Use of product names is for identification only and does not imply 
endorsement by the Public Health Service or the U.S. Department of 
Health and Human Services.

D. After adding disinfectant and dispersant, continue circulating the 
water through the system. Monitor FRC with an FRC-measuring device, 
e.g., a swimming pool test kit, and measure pH with a pH meter every 15 
minutes for 2 hours. Add chlorine as needed to maintain FRC at 
10 mg/L. Adjust pH to 7.5-8.0. The pH may be lowered by 
using any acid (e.g., muriatic acid or sulfuric acid used for 
maintenance of swimming pools) that is compatible with treatment 
chemicals.
E. Two hours after adding disinfectant and dispersant or after FRC 
level is stable at 10 mg/L, monitor at 2-hour intervals and 
maintain FRC at 10 mg/L for 24 hours.
F. After FRC level is maintained at 10 mg/L for 24 hours, 
drain the system. CT/EC water may be drained to the sanitary sewer. 
Municipal water and sewerage authorities should be contacted regarding 
local regulations. If a sanitary sewer is not available, consult local 
or state authorities (e.g. Department of Natural Resources) regarding 
disposal of water. If necessary, drain-off may be dechlorinated by 
dissipation or chemical neutralization (i.e. with sodium bisulfite).
G. Refill system with water and repeat procedure outlined in steps 2-6.
III. Mechanical Cleaning
A. After water from the second chemical disinfection has been drained, 
shut down the CT/EC.
B. Inspect all water contact areas for sediment, sludge, and scale. 
Using brushes and/or a low-pressure water hose, thoroughly clean all 
CT/EC water contact areas including basin, sump, fill, spray nozzles, 
and fittings. Replace components as needed.
C. If possible, clean CT/EC water contact areas within the chillers.
IV. After Mechanical Cleaning
A. Fill system with water, and add chlorine to achieve FRC level of 10 
mg/L.
B. Circulate water for one hour, then open blowdown valve and flush the 
entire system until it is free of turbidity.
C. Drain system.
D. Open any air intake vents that were closed prior to cleaning.
E. Fill system with water. CT/EC may be put back into service using an 
effective water-treatment program.

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