American Thoracic Society Documents
Guidelines for the Management of Adults with
Hospital-acquired, Ventilator-associated, and
Healthcare-associated Pneumonia
This official statement of the American Thoracic Society and the Infectious Diseases Society of America was approved
by the ATS Board of Directors, December 2004 and the IDSA Guideline Committee, October 2004
CONTENTS
Executive Summary
Introduction
Methodology Used to Prepare the Guideline
Epidemiology
Incidence
Etiology
Major Epidemiologic Points
Pathogenesis
Major Points for Pathogenesis
Modifiable Risk Factors
Intubation and Mechanical Ventilation
Aspiration, Body Position, and Enteral Feeding
Modulation of Colonization: OralAntiseptics andAntibiotics
Stress Bleeding Prophylaxis, Transfusion, and Glucose Control
Major Points and Recommendations for Modifiable
Risk Factors
Diagnostic Testing
Major Points and Recommendations for Diagnosis
Diagnostic Strategies and Approaches
Clinical Strategy
Bacteriologic Strategy
Recommended Diagnostic Strategy
Major Points and Recommendations for Comparing
Diagnostic Strategies
Antibiotic Treatment of Hospital-acquired Pneumonia
General Approach
Initial Empiric Antibiotic Therapy
Appropriate Antibiotic Selection and Adequate Dosing
Local Instillation and Aerosolized Antibiotics
Combination versus Monotherapy
Duration of Therapy
Major Points and Recommendations for Optimal
Antibiotic Therapy
Specific Antibiotic Regimens
Antibiotic Heterogeneity and Antibiotic Cycling
Response to Therapy
Modification of Empiric Antibiotic Regimens
Defining the Normal Pattern of Resolution
Reasons for Deterioration or Nonresolution
Evaluation of the Nonresponding Patient
Major Points and Recommendations for Assessing
Response to Therapy
Suggested Performance Indicators
EXECUTIVE SUMMARY
Since the initial 1996 American Thoracic Society (ATS) guide-
line on nosocomial pneumonia, a number of new developments
Am J Respir Crit Care Med Vol 171. pp 388–416, 2005
DOI: 10.1164/rccm.200405-644ST
Internet address: www.atsjournals.org
have appeared, mandating a new evidence-based guideline for
hospital-acquired pneumonia (HAP), including healthcare-asso-
ciated pneumonia (HCAP) and ventilator-associated pneumonia
(VAP). This document, prepared by a joint committee of the
ATS and Infectious Diseases Society of America (IDSA), fo-
cuses on the epidemiology and pathogenesis of bacterial pneu-
monia in adults, and emphasizes modifiable risk factors for infec-
tion. In addition, the microbiology of HAP is reviewed, with an
emphasis on multidrug-resistant (MDR) bacterial pathogens,
such as Pseudomonas aeruginosa, Acinetobacter species, and
methicillin-resistant Staphylococcus aureus. Controversies about
diagnosis are discussed, emphasizing initial examination of lower
respiratory tract samples for bacteria, and the rationale for both
clinical and bacteriologic approaches, using either “semiquanti-
tative” or “quantitative” microbiologic methods that help direct
selection of appropriate antibiotic therapy. We also provide rec-
ommendations for additional diagnostic and therapeutic evalua-
tions in patients with nonresolving pneumonia. This is an evi-
dence-based document that emphasizes the issues of VAP,
because there are far fewer data available aboutHAP in nonintu-
bated patients and about HCAP. By extrapolation, patients who
are not intubated and mechanically ventilated should be man-
aged like patients with VAP, using the same approach to identify
risk factors for infection with specific pathogens.
Themajor goals of this evidence-based guideline for the man-
agement ofHAP,VAP, andHCAPemphasize early, appropriate
antibiotics in adequate doses, while avoiding excessive antibiot-
ics by de-escalation of initial antibiotic therapy, based on micro-
biologic cultures and the clinical response of the patient, and
shortening the duration of therapy to the minimum effective
period. The guideline recognizes the variability of bacteriology
from one hospital to another and from one time period to an-
other and recommends taking local microbiologic data into ac-
count when adapting treatment recommendations to any specific
clinical setting. The initial, empiric antibiotic therapy algorithm
includes two groups of patients: one with no need for broad-
spectrum therapy, because these patients have early-onset HAP,
VAP, or HCAP and no risk factors for MDR pathogens, and a
second group that requires broad-spectrum therapy, because of
late-onset pneumonia or other risk factors for infection with
MDR pathogens.
Some of the key recommendations and principles in this new,
evidence-based guideline are as follows:
• HCAP is included in the spectrum of HAP and VAP, and
patients with HCAP need therapy for MDR pathogens.
• A lower respiratory tract culture needs to be collected
from all patients before antibiotic therapy, but collection
of cultures should not delay the initiation of therapy in
critically ill patients.
• Either “semiquantitative” or “quantitative” culture data
can be used for the management of patients with HAP.
• Lower respiratory tract cultures can be obtained broncho-

American Thoracic Society Documents 389
scopically or nonbronchoscopically, and can be cultured
quantitatively or semiquantitatively.
• Quantitative cultures increase specificity of the diagnosis
of HAP without deleterious consequences, and the specific
quantitative technique should be chosen on the basis of
local expertise and experience.
• Negative lower respiratory tract cultures can be used to
stop antibiotic therapy in a patient who has had cultures
obtained in the absence of an antibiotic change in the past
72 hours.
• Early, appropriate, broad-spectrum, antibiotic therapy
should be prescribed with adequate doses to optimize anti-
microbial efficacy.
• An empiric therapy regimen should include agents that are
from a different antibiotic class than the patient has re-
cently received.
• Combination therapy for a specific pathogen should be
used judiciously in the therapy of HAP, and consideration
should be given to short-duration (5 days) aminoglycoside
therapy, when used in combination with a
-lactam to treat
P. aeruginosa pneumonia.
• Linezolid is an alternative to vancomycin, and uncon-
firmed, preliminary data suggest it may have an advantage
for proven VAP due to methicillin-resistant S. aureus.
• Colistin should be considered as therapy for patients with
VAP due to a carbapenem-resistant Acinetobacter species.
• Aerosolized antibiotics may have value as adjunctive ther-
apy in patients with VAP due to some MDR pathogens.
• De-escalation of antibiotics should be considered once data
are available on the results of lower respiratory tract cul-
tures and the patient’s clinical response.
• A shorter duration of antibiotic therapy (7 to 8 days) is
recommended for patients with uncomplicatedHAP,VAP,
or HCAP who have received initially appropriate therapy
and have had a good clinical response, with no evidence
of infection with nonfermenting gram-negative bacilli.
INTRODUCTION
As with all guidelines, these new recommendations, although
evidence graded, need validation for their impact on the outcome
of patients with HAP, VAP, and HCAP. In addition, this guide-
line points out areas of incomplete knowledge, which can be
used to set an agenda for future research.
Hospital-acquired pneumonia (HAP), ventilator-associated
pneumonia (VAP), and healthcare-associated pneumonia (HCAP)
remain important causes of morbidity and mortality despite ad-
vances in antimicrobial therapy, better supportive care modal-
ities, and the use of a wide-range of preventive measures (1–5).
HAP is defined as pneumonia that occurs 48 hours or more after
admission, which was not incubating at the time of admission
(1, 3).HAPmay bemanaged in a hospital ward or in the intensive
care unit (ICU) when the illness is more severe. VAP refers to
pneumonia that arises more than 48–72 hours after endotracheal
intubation (2, 3). Although not included in this definition, some
patients may require intubation after developing severe HAP
and should be managed similar to patients with VAP. HCAP
includes any patient who was hospitalized in an acute care hospi-
tal for two or more days within 90 days of the infection; resided
in a nursing home or long-term care facility; received recent
intravenous antibiotic therapy, chemotherapy, or wound care
within the past 30 days of the current infection; or attended a
hospital or hemodialysis clinic (3, 4, 6). Although this document
focuses more on HAP and VAP, most of the principles overlap
with HCAP. Because most of the current data have been col-
lected from patients with VAP, and microbiologic data from
nonintubated patients may be less accurate, most of our informa-
tion is derived from those with VAP, but by extrapolation can
be applied to all patients with HAP, emphasizing risk factors
for infection with specific pathogens.
This guideline is an update of the 1996 consensus statement
on HAP published by the American Thoracic Society (5). The
principles and recommendations are largely based on data pre-
sented by committee members at a conference jointly sponsored
by the American Thoracic Society (ATS) and the Infectious
Disease Society of America (IDSA). The committee was com-
posed of pulmonary, critical care, and infectious disease special-
ists with clinical and research interests inHAP,VAP, andHCAP.
All major aspects of the epidemiology, pathogenesis, bacteriol-
ogy, diagnosis, and antimicrobial treatment were reviewed by
this group. Therapy recommendations are focused on antibiotic
choice and patient stratification; adjunctive, nonantibiotic ther-
apy of pneumonia is not discussed, but information on this topic
is available elsewhere (7). Recommendations to reduce the risk
of pneumonia are limited in this document to key, modifiable
risk factors related to the pathogenesis of pneumonia to avoid
redundancy with the more comprehensive Guidelines for Pre-
venting Health-care–associated Pneumonia, prepared by the Cen-
ters for Disease Control and Prevention (CDC) and the Hospital
Infection Control Practices Advisory Committee (HICPAC) (3).
The goal of our document is to provide a framework for the
initial evaluation and management of the immunocompetent,
adult patient with bacterial causes of HAP, VAP, or HCAP,
and excludes patients who are known to be immunosuppressed
by human immunodeficiency virus (HIV) infection, hematologic
malignancy, chemotherapy-induced neutropenia, organ trans-
plantation, and so on. At the outset, the ATS/IDSA Guideline
Committee members recognized that currently, many patients
with HAP, VAP, or HCAP are infected with multidrug-resistant
(MDR) bacterial pathogens that threaten the adequacy of initial,
empiric antibiotic therapy. At the same time, the committee
members recognized that many studies have shown that exces-
sive antibiotic use is a major factor contributing to increased
frequency of antibiotic-resistant pathogens. Four major princi-
ples underlie the management of HAP, VAP, and HCAP:
• Avoid untreated or inadequately treated HAP, VAP, or
HCAP, because the failure to initiate prompt appropriate
and adequate therapy has been a consistent factor associ-
ated with increased mortality.
• Recognize the variability of bacteriology from one hospital
to another, specific sites within the hospital, and from one
time period to another, and use this information to alter the
selection of an appropriate antibiotic treatment regimen for
any specific clinical setting.
• Avoid the overuse of antibiotics by focusing on accurate
diagnosis, tailoring therapy to the results of lower respira-
tory tract cultures, and shortening duration of therapy to
the minimal effective period.
• Apply prevention strategies aimed at modifiable risk fac-
tors.
TheATS/IDSA guideline was established for use in the initial
management of patients in whom HAP, VAP, or HCAP is sus-
pected. Therapeutic algorithms are presented that are based on
the expected antimicrobial susceptibility of the common bacte-
rial pathogens, andwith therapeutic regimens that can commonly
lead to initial adequate antibiotic management.
This guideline is not meant to replace clinical judgment, but
rather to give an organizational framework to patient manage-
ment. Individual clinical situations can be highly complex and
the judgment of a knowledgeable physician with all available
information about a specific patient is essential for optimal clini-