Diagnosis and Treatment of Adults with Community-Acquired Pneumonia

Publication Date: October 1, 2019
Last Updated: December 15, 2022

Diagnosis

1. Gram Stain

We recommend NOT obtaining sputum Gram stain and culture routinely in adults with CAP managed in the outpatient setting. (S, VL)
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We recommend obtaining pretreatment Gram stain and culture of respiratory secretions in adults with CAP managed in the hospital setting who:
1. are classified as severe CAP (see Table 1), especially if they are intubated or (S, VL)

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2.a. are being empirically treated for MRSA or P. aeruginosa (strong recommendation, very low quality of evidence) or (S, VL)

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2.b. were previously infected with MRSA or P. aeruginosa, especially those with prior respiratory tract infection (conditional recommendation, very low quality of evidence) or (C, VL)
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2.c. were hospitalized and received parenteral antibiotics in the last 90 days. (C, VL)
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2. Blood Cultures

We recommend NOT obtaining blood cultures in adults with CAP managed in the outpatient setting. (S, VL)
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We suggest NOT routinely obtaining blood cultures in adults with CAP managed in the hospital setting. (C, VL)
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We recommend obtaining pretreatment blood cultures in adults with CAP managed in the hospital setting who:
1. are classified as severe CAP (see Table 1) or (S, VL)
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2.a. are being empirically treated for MRSA or P. aeruginosa or (S, VL)
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2.b. were previously infected with MRSA or P. aeruginosa, especially those with prior respiratory tract infection or (C, VL)
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2.c. were hospitalized and received parenteral antibiotics, whether during the hospitalization event or not, in the last 90 days. (C, VL)
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3. Urinary Antigens

We suggest NOT routinely testing urine for pneumococcal antigen in adults with CAP (C, L)
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except in adults with severe CAP. (C, L)
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We suggest NOT routinely testing urine for Legionella antigen in adults with CAP except
(C, L)
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1. in cases where indicated by epidemiological factors, such as association with a Legionella outbreak or recent travel, or (C, L)
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2. in adults with severe CAP (See Table 1). (C, L)
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We suggest testing for Legionella urinary antigen and collecting lower respiratory tract secretions for Legionella culture on selective media or Legionella nucleic acid amplification testing in adults with severe CAP. (C, L)
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4. Respiratory Sampling

When influenza viruses are circulating in the community, we recommend testing for influenza with a rapid influenza molecular assay (i.e., influenza nucleic acid amplification test), which is preferred over a rapid influenza diagnostic test (i.e., antigen test). (S, M)
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Treatment

5. Procalcitonin

We recommend that empiric antibiotic therapy should be initiated in adults with clinically suspected and radiographically confirmed CAP regardless of initial serum procalcitonin level. (S, M)
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6. Inpatient Versus Outpatient

In addition to clinical judgment, we recommend that clinicians use a validated clinical prediction rule for prognosis, preferentially the Pneumonia Severity Index (PSI) (S, M)
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over the CURB-65 (tool based on confusion, urea level, respiratory rate, blood pressure, and age ≥65). (C, L)
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to determine the need for hospitalization in adults diagnosed with CAP.

7. Treatment Intensity

We recommend direct admission to an ICU for patients with hypotension requiring vasopressors or respiratory failure requiring mechanical ventilation. (S, L)
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For patients not requiring vasopressors or mechanical ventilator support, we suggest using the IDSA/ATS 2007 minor severity criteria (see Table 1) together with clinical judgment to guide the need for higher levels of treatment intensity. (C, L)
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8. Empiric Antibiotics – Outpatient

For healthy outpatient adults without comorbidities listed below or risk factors for antibiotic resistant pathogens (see Table 2), we recommend:
Amoxicillin 1 g three times daily, or (S, M)
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Doxycycline 100 mg twice daily, or (C, L)
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A macrolide (azithromycin 500 mg on first day then 250 mg daily or clarithromycin 500 mg twice daily or clarithromycin extended release 1,000 mg daily) only in areas with pneumococcal resistance to macrolides <25%. (C, M)
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For outpatient adults with comorbidities such as chronic heart, lung, liver, or renal disease; diabetes mellitus; alcoholism; malignancy; or asplenia we recommend (in no particular order of preference) (see Table 2):
Combination therapy:
  • Amoxicillin/clavulanate 500 mg/125 mg three times daily, or amoxicillin/clavulanate 875 mg/125 mg twice daily, or 2,000 mg/125 mg twice daily, or a cephalosporin (cefpodoxime 200 mg twice daily or cefuroxime 500 mg twice daily); and
  • Macrolide (azithromycin 500 mg on first day then 250 mg daily, clarithromycin [500 mg twice daily or extended release 1,000 mg once daily]
(S, M)
for combination therapy.
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or doxycycline 100 mg twice daily, or (C, L)
for combination therapy.
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Monotherapy:
  • Respiratory fluoroquinolone (levofloxacin 750 mg daily, moxifloxacin 400 mg daily, or gemifloxacin 320 mg daily).
(S, M)
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9. Empiric Antibiotics – Inpatient

In inpatient adults with non-severe CAP without risk factors for MRSA or P. aeruginosa (see Section 11), we recommend the following empiric treatment regimens (in no order of preference):
combination therapy with a beta-lactam (ampicillin+sulbactam 1.5–3 g every 6 hours, cefotaxime 1–2 g every 8 hours, ceftriaxone 1–2 g daily, or ceftaroline 600 mg every 12 hours) and a macrolide (azithromycin 500 mg daily or clarithromycin 500 mg twice daily); or (S, H)
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monotherapy with a respiratory fluoroquinolone (levofloxacin 750 mg daily, moxifloxacin 400 mg daily). (S, H)
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A third option for adults with CAP who have contraindications to both macrolides and fluoroquinolones is:
  • combination therapy with a beta-lactam (ampicillin+sulbactam, cefotaxime, ceftaroline or ceftriaxone, doses as above) and doxycycline 100 mg twice daily.
(C, L)
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In inpatient adults with severe CAP without risk factors for MRSA or P. aeruginosa, we recommend (Note: specific agents and doses are the same as above):
a beta-lactam plus a macrolide; or (S, M)
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a beta-lactam plus a respiratory fluoroquinolone. (S, M)
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10. Suspected Aspiration

We suggest NOT routinely adding anaerobic coverage for suspected aspiration pneumonia unless lung abscess or empyema is suspected. (C, VL)
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11. Extended-spectrum Antibiotics

We recommend abandoning use of the prior categorization of healthcare-associated pneumonia (HCAP) to guide selection of extended antibiotic coverage in adults with CAP. (S, M)
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We recommend clinicians cover empirically only for MRSA or P. aeruginosa in adults with CAP if locally validated risk factors for either pathogen are present. (S, M)
Empiric treatment options for MRSA include vancomycin (15 mg/kg every 12 hours, adjust based on levels), or linezolid (600 mg every 12 hours). Empiric treatment options for P. aeruginosa include piperacillin-tazobactam (4.5 g every 6 hours), cefepime (2 g every 8 hours), ceftazidime (2 g every 8 hours), aztreonam (2 g every 8 hours), meropenem (1 g every 8 hours) or imipenem (500 mg every 6 hours).
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If clinicians are currently covering empirically for MRSA or P. aeruginosa in adults with CAP on the basis of published risk factors but do not have local etiological data, we recommend continuing empiric coverage while obtaining culture data to establish if these pathogens are present to justify continued treatment for these pathogens after the first few days of empiric treatment. (S, L)
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12. Steroids

We recommend NOT routinely using corticosteroids in adults with nonsevere CAP. (S, H)
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We suggest NOT routinely using corticosteroids in adults with severe CAP. (C, M)
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We suggest NOT routinely using corticosteroids in adults with severe influenza pneumonia. (C, L)
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We endorse the Surviving Sepsis Campaign recommendations on the use of corticosteroids in patients with CAP and refractory septic shock. (, )
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13. Antivirals

We recommend that anti-influenza treatment, such as oseltamivir, be prescribed for adults with CAP who test positive for influenza in the inpatient setting, independent of duration of illness before diagnosis. (S, M)
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We suggest that anti-influenza treatment be prescribed for adults with CAP who test positive for influenza in the outpatient setting, independent of duration of illness before diagnosis. (C, L)
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14. Antibiotics for Test-Positive Influenza

We recommend that standard antibacterial treatment be initially prescribed for adults with clinical and radiographic evidence of CAP who test positive for influenza in the inpatient and outpatient settings. (S, L)
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15. Treatment Duration

We recommend that the duration of antibiotic therapy should be guided by a validated measure of clinical stability (resolution of vital sign abnormalities [heart rate, respiratory rate, blood pressure, oxygen saturation, and temperature], ability to eat, and normal mentation), and antibiotic therapy should be continued until the patient achieves stability and for no less than a total of 5 days. (S, M)
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16. Follow-up X-ray

In adults with CAP whose symptoms have resolved within 5-7 days, we suggest NOT routinely obtaining follow-up chest imaging. (C, L)
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Recommendation Grading

Overview

Title

Diagnosis and Treatment of Adults with Community-Acquired Pneumonia

Authoring Organizations

American Thoracic Society

Infectious Diseases Society of America

Publication Month/Year

October 1, 2019

Last Updated Month/Year

November 22, 2024

Document Type

Guideline

External Publication Status

Published

Country of Publication

US

Document Objectives

This guideline addresses the clinical entity of pneumonia that is acquired outside of the hospital setting.  This guideline also focuses on adults who do not have an immunocompromising condition, such as inherited or acquired immune deficiency or drug-induced neutropenia, including patients actively receiving cancer chemotherapy, patients infected with HIV with suppressed CD4 counts, and solid organ or bone marrow transplant recipients.

Target Patient Population

Adult patients with community-acquired pneumonia.

PICO Questions

  1. In Adults with CAP, Should Gram Stain and Culture of Lower Respiratory Secretions Be Obtained at the Time of Diagnosis?

  2. In Adults with CAP, Should Blood Cultures Be Obtained at the Time of Diagnosis?

  3. In Adults with CAP, Should Legionella and Pneumococcal Urinary Antigen Testing Be Performed at the Time of Diagnosis?

  4. In Adults with CAP, Should a Respiratory Sample Be Tested for Influenza Virus at the Time of Diagnosis?

  5. In Adults with CAP, Should Serum Procalcitonin plus Clinical Judgment versus Clinical Judgment Alone Be Used to Withhold Initiation of Antibiotic Treatment?

  6. Should a Clinical Prediction Rule for Prognosis plus Clinical Judgment versus Clinical Judgment Alone Be Used to Determine Inpatient versus Outpatient Treatment Location for Adults with CAP?

  7. Should a Clinical Prediction Rule for Prognosis plus Clinical Judgment versus Clinical Judgment Alone Be Used to Determine Inpatient General Medical versus Higher Levels of Inpatient Treatment Intensity (ICU, Step-Down, or Telemetry Unit) for Adults with CAP?

  8. In the Outpatient Setting, Which Antibiotics Are Recommended for Empiric Treatment of CAP in Adults?

  9. In the Inpatient Setting, Which Antibiotic Regimens Are Recommended for Empiric Treatment of CAP in Adults without Risk Factors for MRSA and P. aeruginosa?

  10. In the Inpatient Setting, Should Patients with Suspected Aspiration Pneumonia Receive Additional Anaerobic Coverage beyond Standard Empiric Treatment for CAP?

  11. In the Inpatient Setting, Should Adults with CAP and Risk Factors for MRSA or P. aeruginosa Be Treated with Extended-Spectrum Antibiotic Therapy Instead of Standard CAP Regimens?

  12. In the Inpatient Setting, Should Adults with CAP Be Treated with Corticosteroids?

  13. In Adults with CAP Who Test Positive for Influenza, Should the Treatment Regimen Include Antiviral Therapy?

  14. In Adults with CAP Who Test Positive for Influenza, Should the Treatment Regimen Include Antibacterial Therapy?

  15. In Outpatient and Inpatient Adults with CAP Who Are Improving, What Is the Appropriate Duration of Antibiotic Treatment?

  16. In Adults with CAP Who Are Improving, Should Follow-up Chest Imaging Be Obtained?

Inclusion Criteria

Male, Female, Adult, Older adult

Health Care Settings

Ambulatory, Hospital

Intended Users

Nurse, nurse practitioner, physician, physician assistant

Scope

Diagnosis, Treatment

Diseases/Conditions (MeSH)

D011014 - Pneumonia

Keywords

community-acquired pneumonia, pneumonia, CAP

Source Citation

Metlay JP, Waterer GW, Long AC, et al. 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. Am J Respir Crit Care Med. 2019;200(7):e45-e67. doi:10.1164/rccm.201908-1581st.

The guideline was a cooperative effort among the American Thoracic Society and Infectious Diseases Society of America.

Supplemental Methodology Resources

Data Supplement