AMERICAN THORACIC SOCIETY
DOCUMENTS
Diagnosis and Treatment of Adults with Community-acquired
Pneumonia
An Official Clinical Practice Guideline of the American Thoracic Society and
Infectious Diseases Society of America
Joshua P. Metlay*, Grant W. Waterer*, Ann C. Long, Antonio Anzueto, Jan Brozek, Kristina Crothers, Laura A. Cooley,
Nathan C. Dean, Michael J. Fine, Scott A. Flanders, Marie R. Griffin, Mark L. Metersky, Daniel M. Musher,
Marcos I. Restrepo, and Cynthia G. Whitney; on behalf of the American Thoracic Society and Infectious Diseases
Society of America
THIS OFFICIAL CLINICAL PRACTICE GUIDELINE WAS APPROVED BY THE AMERICAN THORACIC SOCIETY MAY 2019 AND THE INFECTIOUS DISEASES SOCIETY OF AMERICA
AUGUST 2019
Background: This document provides evidence-based clinical management decisions. Although some recommendations remain
practice guidelines on the management of adult patients with unchanged from the 2007 guideline, the availability of results from
community-acquired pneumonia. new therapeutic trials and epidemiological investigations led to
revised recommendations for empiric treatment strategies and
Methods: A multidisciplinary panel conducted pragmatic additional management decisions.
systematic reviews of the relevant research and applied Grading of
Recommendations, Assessment, Development, and Evaluation Conclusions: The panel formulated and provided the rationale for
methodology for clinical recommendations. recommendations on selected diagnostic and treatment strategies
for adult patients with community-acquired pneumonia.
Results: The panel addressed 16 specific areas for recommendations
spanning questions of diagnostic testing, determination of site of Keywords: community-acquired pneumonia; pneumonia; patient
care, selection of initial empiric antibiotic therapy, and subsequent management
Contents Question 1: In Adults with CAP, Question 2: In Adults with CAP,
Overview Should Gram Stain and Culture Should Blood Cultures Be
Introduction of Lower Respiratory Secretions Obtained at the Time of Diagnosis?
Methods Be Obtained at the Time of Question 3: In Adults with CAP,
Recommendations Diagnosis? Should Legionella and
*Co–first authors.
Endorsed by the Society of Infectious Disease Pharmacists July 2019.
ORCID IDs: 0000-0003-2259-6282 (J.P.M.); 0000-0002-7222-8018 (G.W.W.); 0000-0002-7007-588X (A.A.); 0000-0002-3122-0773 (J.B.);
0000-0001-9702-0371 (K.C.); 0000-0002-5127-3442 (L.A.C.); 0000-0002-1996-0533 (N.C.D.); 0000-0003-3470-9846 (M.J.F.);
0000-0002-8634-4909 (S.A.F.); 0000-0001-7114-7614 (M.R.G.); 0000-0003-1968-1400 (M.L.M.); 0000-0002-7571-066X (D.M.M.);
0000-0001-9107-3405 (M.I.R.); 0000-0002-1056-3216 (C.G.W.).
Supported by the American Thoracic Society and Infectious Diseases Society of America.
The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the U.S. CDC.
An Executive Summary of this document is available at http://www.atsjournals.org/doi/suppl/10.1164/rccm.201908-1581ST.
You may print one copy of this document at no charge. However, if you require more than one copy, you must place a reprint order. Domestic reprint orders:
amy.schriver@sheridan.com; international reprint orders: louisa.mott@springer.com.
This article has an online supplement, which is accessible from this issue’s table of contents at www.atsjournals.org.
Am J Respir Crit Care Med Vol 200, Iss 7, pp e45–e67, Oct 1, 2019
Copyright © 2019 by the American Thoracic Society
DOI: 10.1164/rccm.201908-1581ST
Internet address: www.atsjournals.org
American Thoracic Society Documents e45
, AMERICAN THORACIC SOCIETY DOCUMENTS
Pneumococcal Urinary Antigen Levels of Inpatient Treatment Extended-Spectrum Antibiotic
Testing Be Performed at the Intensity (ICU, Step-Down, or Therapy Instead of Standard
Time of Diagnosis? Telemetry Unit) for Adults with CAP Regimens?
Question 4: In Adults with CAP, CAP? Question 12: In the Inpatient
Should a Respiratory Sample Be Question 8: In the Outpatient Setting, Should Adults
Tested for Influenza Virus at the Setting, Which Antibiotics Are with CAP Be Treated with
Time of Diagnosis? Recommended for Empiric Corticosteroids?
Question 5: In Adults with CAP, Treatment of CAP in Adults? Question 13: In Adults with CAP
Should Serum Procalcitonin plus Question 9: In the Inpatient Who Test Positive for Influenza,
Clinical Judgment versus Setting, Which Antibiotic Should the Treatment Regimen
Clinical Judgment Alone Be Regimens Are Recommended Include Antiviral Therapy?
Used to Withhold Initiation of for Empiric Treatment of Question 14: In Adults with
Antibiotic Treatment? CAP in Adults without Risk CAP Who Test Positive for
Question 6: Should a Clinical Factors for MRSA and Influenza, Should the Treatment
Prediction Rule for Prognosis P. aeruginosa? Regimen Include Antibacterial
plus Clinical Judgment versus Question 10: In the Inpatient Therapy?
Clinical Judgment Alone Be Setting, Should Patients Question 15: In Outpatient and
Used to Determine Inpatient with Suspected Aspiration Inpatient Adults with CAP Who
versus Outpatient Treatment Pneumonia Receive Additional Are Improving, What Is the
Location for Adults with CAP? Anaerobic Coverage beyond Appropriate Duration of
Question 7: Should a Clinical Standard Empiric Treatment for Antibiotic Treatment?
Prediction Rule for Prognosis CAP? Question 16: In Adults with CAP
plus Clinical Judgment versus Question 11: In the Inpatient Who Are Improving, Should
Clinical Judgment Alone Be Setting, Should Adults with CAP Follow-up Chest Imaging Be
Used to Determine Inpatient and Risk Factors for MRSA or Obtained?
General Medical versus Higher P. aeruginosa Be Treated with Conclusions
Overview imaging. The document does not address defining CAP, given the known inaccuracy
either the initial clinical diagnostic criteria of clinical signs and symptoms alone for
In the more than 10 years since the last or prevention of pneumonia. CAP diagnosis (3). This guideline focuses
American Thoracic Society(ATS)/Infectious CAP is an extraordinarily on patients in the United States who have
Diseases Society of America (IDSA) heterogeneous illness, both in the range not recently completed foreign travel,
community-acquired pneumonia (CAP) of responsible pathogens and the host especially to regions with emerging
guideline (1), there have been changes in response. Thus, the PICO questions we respiratory pathogens. This guideline also
the process for guideline development, as identified for this guideline do not represent focuses on adults who do not have an
well as generation of new clinical data. ATS the full range of relevant questions about the immunocompromising condition, such as
and IDSA agreed on moving from the management of CAP but encompass a set of inherited or acquired immune deficiency or
narrative style of previous documents to the core questions identified as high priority by drug-induced neutropenia, including
Grading of Recommendations Assessment, the panel. In addition, although each patients actively receiving cancer
Development, and Evaluation (GRADE) question was addressed using systematic chemotherapy, patients infected with HIV
format. We thus developed this updated reviews of available high-quality studies, with suppressed CD4 counts, and solid
CAP guideline as a series of questions the evidence base was often insufficient, organ or bone marrow transplant
answered from available evidence in an “is emphasizing the continued importance of recipients.
option A better than option B” format clinical judgment and experience in treating Antibiotic recommendations for the
using the Patient or Population, patients with this illness and the need for empiric treatment of CAP are based on
Intervention, Comparison, Outcome continued research. selecting agents effective against the major
(PICO) framework (2). treatable bacterial causes of CAP.
Given the expansion in information Traditionally, these bacterial pathogens
related to the diagnostic, therapeutic, and Introduction include Streptococcus pneumoniae,
management decisions for the care of Haemophilus influenzae, Mycoplasma
patients with CAP, we have purposely This guideline addresses the clinical entity of pneumoniae, Staphylococcus aureus,
narrowed the scope of this guideline to pneumonia that is acquired outside of the Legionella species, Chlamydia pneumoniae,
address decisions from the time of clinical hospital setting. Although we recognize that and Moraxella catarrhalis. The microbial
diagnosis of pneumonia (i.e., signs and CAP is frequently diagnosed without the use etiology of CAP is changing, particularly
symptoms of pneumonia with radiographic of a chest radiograph, especially in the with the widespread introduction of the
confirmation) to completion of ambulatory setting, we have focused on pneumococcal conjugate vaccine, and there
antimicrobial therapy and follow-up chest studies that used radiographic criteria for is increased recognition of the role of viral
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pathogens. The online supplement contains recommendations to maximize readability b. were previously infected with MRSA
a more detailed discussion of CAP and usability. We followed the GRADE or P. aeruginosa, especially those
microbiology. As bacterial pathogens often standards for evaluating the evidence for with prior respiratory tract infection
coexist with viruses and there is no current each PICO and assigned a quality of (conditional recommendation, very
diagnostic test accurate enough or fast evidence rating of high, moderate, low, or low quality of evidence); or
enough to determine that CAP is due solely very low. On the basis of the quality of c. were hospitalized and received
to a virus at the time of presentation (see evidence, recommendations were assigned parenteral antibiotics, whether during the
below), our recommendations are to as strong or conditional. In some cases, hospitalization event or not, in the last
initially treat empirically for possible strong recommendations were made in the 90 days (conditional recommendation,
bacterial infection or coinfection. In setting of low or very low quality of evidence very low quality of evidence).
addition, the emergence of multidrug- in accordance with the GRADE rules for Summary of the evidence. Arguments
resistant pathogens, including methicillin- when such recommendations are allowable for trying to determine the etiology of CAP
resistant S. aureus (MRSA) and (e.g., when the consequences of the are that 1) a resistant pathogen may be
Pseudomonas aeruginosa, requires separate recommendation were high, such as identified; 2) therapy may be narrowed; 3)
recommendations when the risk of preventing harm or saving life). In all other some pathogens, such as Legionella, have
each of these pathogens is elevated. We cases, recommendations that were based on public health implications; 4) therapy may
acknowledge that other multidrug-resistant low or very low quality of evidence and not be adjusted when patients fail initial
Enterobacteriaceae can cause CAP, believed to represent standards of care were therapy; and 5) the constantly changing
including organisms producing extended- labeled as conditional recommendations. epidemiology of CAP requires ongoing
spectrum b-lactamase, but we do not Statements in favor of strong evaluation.
discuss them separately because they are recommendations begin with the words These arguments stand in contrast to
much less common and are effectively “We recommend . . .”; statements in favor the lack of high-quality evidence
covered by the strategies presented for of conditional recommendations begin demonstrating that routine diagnostic
P. aeruginosa. Therefore, throughout this with the words “We suggest . . . .” testing improves individual patient
document when discussing P. aeruginosa Although we specified pairwise PICO outcomes. Studies that specifically evaluated
we are also referring to other similar questions for all antibiotic options in the the use of sputum Gram stain and culture
multiresistant gram-negative bacteria. outpatient and inpatient settings, we alone (4–7), or in combination with other
We have maintained the convention summarized the recommendations using microbiological testing (8–11), also did not
of separate recommendations on the lists of treatment options, in no preferred demonstrate better patient outcomes.
basis of the severity of illness. Although order, rather than retain the PICO format The overall poor yield of sputum
historically site of care (outpatient, for this section. evaluation for detecting organisms causing
inpatient general ward, or ICU) has served CAP limits its impact on management and
as a severity surrogate, decisions about site patient outcomes. Obtaining a valid sputum
of care may be based on considerations specimen can be challenging because of
other than severity and can vary widely
Recommendations patient-related characteristics (12–17).
between hospitals and practice sites. Performance characteristics of testing also
Question 1: In Adults with CAP,
We have therefore chosen to use the vary by organism, receipt of prior
Should Gram Stain and Culture of
IDSA/ATS CAP severity criteria that have antibiotics, and setting. For example, in
Lower Respiratory Secretions Be
been validated and define severe CAP as patients with bacteremic pneumococcal
Obtained at the Time of Diagnosis?
present in patients with either one major pneumonia who have not received
criterion or three or more minor criteria. antibiotics, microscopic examination and
Recommendation. We recommend not
(Table 1) culture of a good-quality sputum sample
obtaining sputum Gram stain and culture
This guideline reaffirms many detects pneumococci in 86% of cases (18).
routinely in adults with CAP managed in the
recommendations from the 2007 statement. Rationale for the recommendation. In
outpatient setting (strong recommendation,
However, new evidence and a new process balancing the lack of evidence supporting
very low quality of evidence).
have led to significant changes, which are routine sputum culture with the desire for
We recommend obtaining pretreatment
summarized in Table 2. improved antimicrobial stewardship, the
Gram stain and culture of respiratory
committee voted to continue the stance of
secretions in adults with CAP managed in
previous guidelines in recommending
the hospital setting who:
Methods neither for nor against routinely obtaining
1. are classified as severe CAP (see Table 1), sputum Gram stain and culture in all adults
The guideline development methodology especially if they are intubated (strong with CAP managed in the hospital setting.
and how conflict of interest was managed recommendation, very low quality of Whether to culture patients or not should be
are presented in the online supplement. In evidence); or determined by individual clinicians on the
brief, the list of PICO questions was finalized 2. basis of clinical presentation, local
based on a prioritization of the most a. are being empirically treated for etiological considerations, and local
important management decisions balanced MRSA or P. aeruginosa (strong antimicrobial stewardship processes.
against the decision to reduce the overall recommendation, very low quality The committee identified two
length of the document and total number of of evidence); or situations in which we recommend sputum
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