EMA Cited · Infectious disease · Pulmonary

Community-acquired pneumonia

Updated Nov 2, 2026Adults · ED management13 sources · 10 checked in PubMed2 figuresATS/IDSA 2019 · ATS 2025

Bottom line

Confirm the diagnosis with imaging. Start antibiotics for clinically suspected, radiographically confirmed CAP whatever the procalcitonin.¹ Lung ultrasound is an acceptable alternative to a chest X-ray where there is expertise.^2,3
Use the PSI plus judgment to decide on admission, and send patients needing vasopressors or ventilation straight to the ICU.¹
Match antibiotics to the setting. Healthy outpatients: amoxicillin. Comorbid outpatients and ward patients: a beta-lactam plus a macrolide, or a respiratory fluoroquinolone. Cover MRSA or Pseudomonas only with locally validated risk factors.¹
Shorter courses are now advised. For clinically stable outpatients, ATS 2025 suggests fewer than 5 days, with a minimum of 3.^2,3
No steroids in non-severe CAP (strong recommendation).^1,3 ATS 2025 suggests them in severe CAP, but the large trials disagree.^3,4,5,6

Diagnosis and testing

Frontal chest radiograph showing a hazy white opacity in the right lower lung zone beside the right heart border — FIG 1Right middle lobe pneumonia. Frontal chest X-ray with an airspace opacity in the right lower zone, next to the right heart border.Mikael Häggström, MD · Wikimedia Commons · CC0

Lung ultrasound may replace the chest X-ray where clinicians have expertise (conditional, low quality, ATS 2025).^2,3 In a meta-analysis of ED studies, consolidation had a sensitivity of 82% and specificity of 94% for pneumonia.⁷
Procalcitonin should not decide whether to start antibiotics (strong, moderate quality).¹
Influenza: when it is circulating, test with a rapid molecular assay rather than an antigen test (strong, moderate quality).¹
Blood and sputum cultures: not for outpatients. In admitted patients, send them before antibiotics for severe CAP, empiric MRSA or Pseudomonas treatment, prior MRSA or Pseudomonas infection, or hospitalization with IV antibiotics in the last 90 days.¹
Urinary antigens for pneumococcus and Legionella: not routinely, except in severe CAP or, for Legionella, an outbreak or recent travel.¹

Severity and where to treat

Home or hospital: use the Pneumonia Severity Index (PSI) with clinical judgment (strong, moderate quality), in preference to CURB-65 (conditional, low).¹ In the PSI derivation and validation cohorts, 30-day mortality was 0.1–0.4% in class I, 0.6–0.7% in class II and 0.9–2.8% in class III.⁸
CURB-65 gives one point each for confusion, urea > 7 mmol/L, respiratory rate ≥ 30, low blood pressure and age ≥ 65. Mortality was 0.7% at score 0 and 57% at score 5.⁹
Beyond the score: inability to keep up oral intake, substance use, cognitive impairment, severe comorbid illness or poor function may each rule out home treatment.¹
ICU directly for hypotension needing vasopressors or respiratory failure needing mechanical ventilation (strong). Otherwise, use the minor criteria below with judgment to decide on a higher level of care (conditional).¹

Severe CAP: 1 major or ≥ 3 minor criteria
Major
Septic shock needing vasopressors
Respiratory failure needing mechanical ventilation
Minor
Respiratory rate ≥ 30/min	PaO₂/FiO₂ ≤ 250
Multilobar infiltrates	Confusion or disorientation
BUN ≥ 20 mg/dL	WBC < 4,000/µL (from infection)
Platelets < 100,000/µL	Core temperature < 36 °C
Hypotension needing aggressive fluids

The 2007 IDSA/ATS criteria, kept in the 2019 guideline.¹

Antibiotics

FIG 2 · Decision flowCited

Suspected CAP. Confirm with a chest X-ray, or lung ultrasound where there is expertise. Start antibiotics whatever the procalcitonin.^1,2,3
Needs vasopressors or mechanical ventilation?
Yes
Admit directly to the ICU.¹
Either way
Severe CAP: 1 major or 3 or more minor criteria?
Yes
Blood and sputum cultures, then a beta-lactam plus a macrolide (or plus a respiratory fluoroquinolone).¹
Steroids: suggested by ATS 2025, but trials conflict.^3,4,6
No
Home or ward? Use the PSI with judgment, and weigh oral intake, cognition, comorbidity and function.¹
Admitted to the ward?
Yes
Beta-lactam plus macrolide, or a respiratory fluoroquinolone.¹
Add MRSA or Pseudomonas cover only with locally validated risk factors, and culture first.¹
No, going home
Home: amoxicillin 1 g three times daily if healthy. With comorbidities, amoxicillin-clavulanate or a cephalosporin plus a macrolide or doxycycline, or a respiratory fluoroquinolone alone.¹
Influenza positive: oseltamivir for inpatients, and suggested for outpatients.¹ A healthy outpatient with a positive viral test may not need antibiotics.^2,3
How long: until clinically stable. ATS 2025 suggests fewer than 5 days (at least 3) for stable outpatients; the 2019 guideline said at least 5.^1,2,3

FIG 2CAP in the emergency department. Drawn for this page from the ATS/IDSA 2019 and ATS 2025 guidelines. Each box carries its own citations.^1,2,3

Setting	Adult regimen and dose	Strength
Outpatient, no comorbidities
First choice	Amoxicillin 1 g three times daily	Strong, moderate
Alternative	Doxycycline 100 mg twice daily	Conditional, low
Only if pneumococcal macrolide resistance < 25%	Azithromycin 500 mg day 1, then 250 mg daily	Conditional, moderate
Outpatient with comorbidities (heart, lung, liver or kidney disease, diabetes, alcohol use disorder, cancer, asplenia)
Combination	Amoxicillin-clavulanate 875/125 mg twice daily, or cefpodoxime 200 mg or cefuroxime 500 mg twice daily; plus azithromycin (as above) or doxycycline 100 mg twice daily	Strong, moderate (with macrolide)
Monotherapy	Levofloxacin 750 mg daily or moxifloxacin 400 mg daily	Strong, moderate
Inpatient, non-severe
Combination	Ceftriaxone 1–2 g daily (or ampicillin-sulbactam 1.5–3 g every 6 h) plus azithromycin 500 mg daily	Strong, high
Monotherapy	Levofloxacin 750 mg daily or moxifloxacin 400 mg daily	Strong, high
Inpatient, severe
Preferred	Beta-lactam plus macrolide (doses as above)	Strong, moderate
Alternative	Beta-lactam plus respiratory fluoroquinolone	Strong, low
Add only with locally validated risk factors
MRSA	Vancomycin 15 mg/kg every 12 h, adjusted to levels, or linezolid 600 mg every 12 h	Strong, moderate
Pseudomonas	Piperacillin-tazobactam 4.5 g every 6 h, cefepime 2 g every 8 h, or meropenem 1 g every 8 h	Strong, moderate
Influenza-positive CAP
Antiviral	Oseltamivir 75 mg twice daily for 5 days; reduce for kidney impairment	Inpatient strong, outpatient conditional

Unreviewed doses. Verify against the current label and your institution's protocol before giving anything.

Antibiotic regimens, doses and strengths from the 2019 ATS/IDSA guideline.¹ Oseltamivir dose from the FDA label.¹⁰ Check the labels for kidney dose adjustments.

Drop the old "healthcare-associated pneumonia" label (strong). The strongest risk factors for MRSA or Pseudomonas are prior respiratory isolation of the organism, and recent hospitalization with IV antibiotics.¹
Suspected aspiration: don't routinely add anaerobic cover unless you suspect a lung abscess or empyema (conditional, very low quality).¹
Influenza: give oseltamivir to inpatients with CAP who test positive, however long they have been ill (strong).¹ The label advises starting within 48 hours of symptom onset.¹⁰
Positive viral test: in 2019, standard antibiotics were recommended for influenza-positive CAP in every setting (strong, low quality).¹ ATS 2025 now suggests withholding them in outpatients without comorbidities who test positive for a respiratory virus (conditional, very low quality).^2,3 Antibiotics are still advised for patients with comorbidities and for those admitted.¹¹

How long to treat

Treat to clinical stability: normal heart rate, respiratory rate, blood pressure, oxygen saturation and temperature, able to eat, and normal mentation.¹
ATS 2025: for outpatients who reach clinical stability, fewer than 5 days, with a minimum of 3 (conditional, low quality).^2,3 A published summary applies the same to admitted patients with non-severe CAP, and 5 days or more to severe CAP.¹¹
PTC trial (303 ward patients stable after 3 days of a beta-lactam): stopping was non-inferior to 5 more days of amoxicillin-clavulanate. Cure at day 15 was 77% with placebo vs 68% with continued antibiotics.¹²
Follow-up imaging: not routinely, if symptoms resolve within 5–7 days (conditional).¹

Guidelines changed

The 2019 ATS/IDSA guideline recommended at least 5 days in total, even after stability (strong, moderate quality).¹ The 2025 ATS update suggests as few as 3 days for stable outpatients (conditional, low quality).^2,3 Follow your local antibiotic stewardship policy until it is updated.

Corticosteroids

Non-severe CAP: no steroids. Both guidelines make this a strong recommendation.^1,3
Severe CAP: ATS 2025 suggests systemic steroids for inpatients (conditional, low quality).³ The 2019 guideline had suggested not routinely using them, and endorsed the Surviving Sepsis Campaign advice for refractory septic shock.¹
Severe influenza pneumonia: the 2019 guideline suggests not routinely giving steroids (conditional, low quality).¹

Trial (severe CAP, ICU)	Steroid	Mortality
CAPE COD, n = 795, blinded	Hydrocortisone 200 mg/day, tapered over 8–14 days	6.2% vs 11.9% at 28 days⁴
ESCAPe, n = 584, blinded	Methylprednisolone 40 mg/day, tapered over 20 days	16% vs 18% at 60 days, not significant⁵
REMAP-CAP, n = 658, open-label	Hydrocortisone 50 mg every 6 h for 7 days	15% vs 9.8% at 90 days; stopped for futility⁶

Trials disagree

CAPE COD found fewer deaths and fewer intubations with hydrocortisone.⁴ ESCAPe found no mortality benefit.⁵ REMAP-CAP found no benefit and could not exclude harm.⁶ Its critics note the open-label design, a coding error that put more patients in the hydrocortisone arm, a slightly sicker hydrocortisone group, and steroid use in 23% of controls.¹³ The doses above are trial doses, not recommendations.

Pitfalls

Withholding antibiotics in confirmed CAP because the procalcitonin is low.¹
Reaching for vancomycin and piperacillin-tazobactam because the patient lives in a nursing home. Use locally validated risk factors instead.¹
Adding anaerobic cover for every suspected aspiration.¹
Using macrolide monotherapy where pneumococcal macrolide resistance is 25% or more.¹
Giving steroids in non-severe CAP.^1,3
Admitting or discharging on the score alone. The PSI is an aid to judgment and may underestimate severity in younger patients.¹

How strong is the evidence?

The core antibiotic regimens for ward patients rest on high-quality evidence.¹ Most testing recommendations rest on very low or low quality evidence.¹ All four 2025 updates are graded low or very low quality.³ The 2025 full text was not openly accessible, so its recommendations are cited from the American Thoracic Society's announcement and a published summary.^2,3,11

On-shift teaching

Questions to ask a learner at the bedside. Tap a question to see the answer. Every answer uses facts cited above.

Q1What makes CAP "severe" under the IDSA/ATS criteria?

One major criterion (vasopressors or mechanical ventilation) or at least three minor ones, such as respiratory rate ≥ 30, PaO₂/FiO₂ ≤ 250, multilobar infiltrates, confusion, BUN ≥ 20 mg/dL or hypotension needing aggressive fluids.¹

Q2Which rule does the 2019 guideline prefer for the home-or-hospital decision?

The PSI (strong recommendation) over CURB-65 (conditional), always with clinical judgment.¹

Q3What is first-line for a healthy outpatient with CAP?

Amoxicillin 1 g three times daily (strong). Doxycycline is an alternative; a macrolide only where pneumococcal macrolide resistance is under 25%.¹

Q4When should you cover MRSA or Pseudomonas?

Only with locally validated risk factors. The strongest are prior respiratory isolation of the organism and recent hospitalization with IV antibiotics. Culture first so you can de-escalate.¹

Q5A ward patient is stable after 3 days of a beta-lactam. Do they need 5 more days?

Probably not. In the PTC trial, stopping was non-inferior: cure at day 15 was 77% with placebo vs 68% with 5 more days.¹² ATS 2025 suggests fewer than 5 days (at least 3) for stable outpatients.^2,3

Q6Do steroids help in severe CAP?

Uncertain. CAPE COD: 28-day mortality 6.2% vs 11.9% with hydrocortisone.⁴ ESCAPe: 16% vs 18%, not significant.⁵ REMAP-CAP: 15% vs 9.8%, stopped for futility.⁶ ATS 2025 conditionally suggests them.³

References

Evidence base

What this page is built on

13 sources, cited 91 times. Dots are sources, filled by how far each was read; stronger color means a larger share of the citations. Tap a tier to see its sources.

Read in full · 4Abstract read · 8Record only · 1Link checked · 0

Checked by the writer, not a physician. The dots show how each source was read, not that anyone has confirmed the claims.

1
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.GuidelinePMID 31573350 PMCFull text read
2
Jones BE, Ramirez JA, Oren E, et al. Diagnosis and management of community-acquired pneumonia: an official American Thoracic Society clinical practice guideline. Am J Respir Crit Care Med. 2026;212(1):24–44.GuidelinePMID 40679934 DOIPubMed record; full text not openly accessible
3
American Thoracic Society. Treatment with antibiotics and steroids in adults with pneumonia addressed in latest clinical practice guideline (news release). November 11, 2025.Guideline summaryeurekalert.orgPage read
4
Dequin PF, Meziani F, Quenot JP, et al. Hydrocortisone in severe community-acquired pneumonia (CAPE COD). N Engl J Med. 2023;388(21):1931–1941.RCTPMID 36942789PubMed
5
Meduri GU, Shih MC, Bridges L, et al. Low-dose methylprednisolone treatment in critically ill patients with severe community-acquired pneumonia (ESCAPe). Intensive Care Med. 2022;48(8):1009–1023.RCTPMID 35723686 PMCPubMed
6
REMAP-CAP Investigators; Angus DC. Effect of hydrocortisone on mortality in patients with severe community-acquired pneumonia: the REMAP-CAP corticosteroid domain randomized clinical trial. Intensive Care Med. 2025;51(4):665–680.RCTPMID 40261382 PMCPubMed
7
Staub LJ, Mazzali Biscaro RR, Kaszubowski E, et al. Lung ultrasound for the emergency diagnosis of pneumonia, acute heart failure, and exacerbations of chronic obstructive pulmonary disease/asthma in adults: a systematic review and meta-analysis. J Emerg Med. 2019;56(1):53–69.Meta-analysisPMID 30314929PubMed
8
Fine MJ, Auble TE, Yealy DM, et al. A prediction rule to identify low-risk patients with community-acquired pneumonia. N Engl J Med. 1997;336(4):243–250.CohortPMID 8995086PubMed
9
Lim WS, van der Eerden MM, Laing R, et al. Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study. Thorax. 2003;58(5):377–382.CohortPMID 12728155 PMCPubMed
10
Oseltamivir phosphate capsules. FDA label, DailyMed.Drug labelDailyMedLabel text read
11
Long B, Gottlieb M. 2025 guideline updates for community-acquired pneumonia diagnosis and management. Am J Emerg Med. 2026;107:16–20.Guideline summaryPMID 42127879PubMed
12
Dinh A, Ropers J, Duran C, et al. Discontinuing β-lactam treatment after 3 days for patients with community-acquired pneumonia in non-critical care wards (PTC): a double-blind, randomised, placebo-controlled, non-inferiority trial. Lancet. 2021;397(10280):1195–1203.RCTPMID 33773631PubMed
13
Connell L. REMAP-CAP: Corticosteroids. The Bottom Line; September 2025.FOAMthebottomline.org.ukPage read

Not for clinical use

AI-generated draft. Not reviewed by a physician. This page is for education only and may contain errors, including in doses. Do not use it to diagnose, treat or make decisions about any patient. Rely on your own clinical judgment, your institution's protocols and current drug labeling. Reading this page does not create a physician-patient relationship. Full terms