Suspected community-acquired pneumonia (adult)
Acute cough or dyspnoea with fever or focal chest signs
All Pathways
Infectious DiseaseManagement
Community-Acquired Pneumonia Management (ATS 2025)
Community-Acquired Pneumonia Management (ATS 2025): Suspected community-acquired pneumonia (adult) → Not for children, immunocompromised adults or HAP/V...
Pathway Overview
21 steps
Algorithm Steps
21 total
01Start 02Warning Not for children, immunocompromised adults or HAP/VAP
This pathway covers immunocompetent adults only
- Children: use a paediatric CAP guideline
- Immunocompromised (chemotherapy, transplant, advanced HIV, neutropenia): seek ID advice
- Hospital-acquired or ventilator-associated pneumonia: use HAP/VAP guidance
03Action Confirm diagnosis: new infiltrate on imaging
Clinical features plus new infiltrate on chest X-ray. Sepsis or shock: give antibiotics within 1 hour; do not wait for imaging
- Symptoms: cough, fever, dyspnoea, pleuritic pain; crackles or bronchial breathing
- Chest X-ray; lung ultrasound is an acceptable alternative where expertise exists
- Influenza circulating: test with a rapid molecular influenza test
- Do not use procalcitonin to withhold antibiotics
04Warning Before antibiotics: pregnancy, QT or vascular risk, allergy
Adjust doses to renal function
- Pregnancy: avoid doxycycline (TGA category D) and fluoroquinolones; use a beta-lactam +/- azithromycin
- Arrhythmia or long QT: caution with macrolides and fluoroquinolones. Vascular disease or aortic aneurysm: avoid fluoroquinolones
- Severe penicillin allergy: nonsevere CAP, fluoroquinolone alone; severe CAP, never fluoroquinolone alone, seek ID advice. Antibiotic in last 90 days: use a different class
05Decision Assess severity and site of care
Clinical judgement plus a validated score: PSI preferred, or CURB-65 (Australia: SMART-COP)
- Low: PSI I-II or CURB-65 0-1, no hypoxaemia, can take oral drugs, support at home
- Consider admission: PSI III or higher or CURB-65 2 or more; hypoxaemia; cannot take oral drugs
- Severe: 1 major or 3 or more minor ATS/IDSA criteria (next steps)
- Low severity
06Action Low severity: treat as outpatient
PSI I-II or CURB-65 0-1; no hypoxaemia; can take oral drugs; support at home
- Positive respiratory virus test and no comorbidity: ATS 2025 suggests no antibacterial
- Influenza positive: oseltamivir 75 mg orally 12-hourly for 5 days (adult; lower dose if CrCl 60 mL/min or less)
- Australia: use eTG Antibiotic regimens and doses
07Decision Outpatient: comorbidity present?
Chronic heart, lung, liver or renal disease; diabetes; alcoholism; malignancy; asplenia
- If Yes
08Action Outpatient with comorbidity: beta-lactam plus macrolide, or fluoroquinolone
Adult oral doses
- Amoxicillin-clavulanate 875/125 mg 12-hourly (or 500/125 mg 8-hourly)
- PLUS azithromycin 500 mg day 1, then 250 mg daily; or doxycycline 100 mg 12-hourly
- OR monotherapy: moxifloxacin 400 mg daily or levofloxacin 750 mg daily (levofloxacin not marketed in Australia)
- Not in pregnancy: doxycycline or fluoroquinolone
09Decision Reassess daily: clinically stable by 48-72 h?
Stable: normal HR, RR, BP, SpO2 and temperature; eating; normal mentation
- If Yes
10Action Stable: oral switch and stop date
Switch to oral when stable, eating and absorbing
- Outpatient or nonsevere CAP: stop before day 5 if stable (minimum 3 days) (ATS 2025)
- Severe CAP: at least 5 days
- MRSA or Pseudomonas: 7 days. Empyema, abscess or melioidosis: longer; seek specialist advice
11Outcome Recovered: discharge and follow-up
No routine follow-up chest imaging if symptoms resolve within 5-7 days
- Smoking cessation advice
- Pneumococcal and influenza vaccination if due
- Return if symptoms worsen or do not resolve
If No12Warning Not stable by 72 h or worsening: look for complications
Consider admission or escalation of care
- Empyema, lung abscess, resistant or unusual organism (TB, melioidosis), or non-infectious cause
- Repeat cultures; CT chest; consider bronchoscopy
- Seek ID or respiratory advice before broadening antibiotics
13Outcome Not improving: specialist review and escalate care
ID or respiratory review; ICU review if deteriorating
If No14Action Outpatient, no comorbidity: amoxicillin or doxycycline
Adult oral doses
- Amoxicillin 1 g 8-hourly
- OR doxycycline 100 mg 12-hourly (not in pregnancy)
- Azithromycin 500 mg day 1, then 250 mg daily: only where pneumococcal macrolide resistance is under 25%
- Path rejoins step 09Shared downstream outcome
- Admit, not severe
15Action Admitted, not severe: beta-lactam plus macrolide
Adult doses. No corticosteroids for nonsevere CAP
- Ceftriaxone 1-2 g IV daily (or cefotaxime 1-2 g IV 8-hourly) PLUS azithromycin 500 mg IV or orally daily
- OR moxifloxacin 400 mg daily or levofloxacin 750 mg daily alone
- Macrolide and fluoroquinolone both unsuitable: beta-lactam plus doxycycline 100 mg 12-hourly
- Influenza positive: oseltamivir 75 mg orally 12-hourly for 5 days (adult; lower dose if CrCl 60 mL/min or less), even after 48 h of symptoms
- Australia: use eTG Antibiotic regimens; ampicillin-sulbactam and levofloxacin are not marketed. Tropical north: seek ID advice (melioidosis, Acinetobacter)
- Suspected aspiration: no routine anaerobic cover unless abscess or empyema
16Decision Admitted: MRSA or Pseudomonas risk?
Prior respiratory isolate of MRSA or P. aeruginosa, or hospitalised with IV antibiotics in the last 90 days. No risk: keep the standard regimen and reassess
- If Yes
17Action MRSA or Pseudomonas risk: cultures, then add cover
Prior isolate: add cover. Recent IV antibiotics only: add cover if severe; if nonsevere, add only when cultures or PCR are positive
- Take blood and sputum cultures before starting
- MRSA, adult: vancomycin loading 20-35 mg/kg actual body weight (max 3000 mg), then AUC-guided dosing (AUC 400-600 mg.h/L) with pharmacy
- OR linezolid 600 mg IV or orally 12-hourly
- Pseudomonas: piperacillin-tazobactam 4.5 g IV 6-hourly, cefepime 2 g IV 8-hourly or meropenem 1 g IV 8-hourly in place of ceftriaxone; keep macrolide
- Negative MRSA nasal PCR or cultures at 48 h: stop the extra cover
- Path rejoins step 09Shared downstream outcome
If No- Path rejoins step 09Shared downstream outcome
- Severe
18Action Severe CAP: ICU or HDU; antibiotics within 1 hour
1 major criterion (shock needing vasopressors, or mechanical ventilation) or 3 or more minor criteria. Do not delay antibiotics for cultures
- Minor: RR 30/min or more; PaO2/FiO2 250 or less; multilobar infiltrates; confusion
- Minor: urea 7 mmol/L or more (BUN 20 mg/dL); WBC under 4 x10^9/L; platelets under 100 x10^9/L
- Minor: temperature under 36 C; hypotension needing aggressive fluid resuscitation
- Before antibiotics, if no delay: blood cultures, sputum Gram stain and culture; also pneumococcal and Legionella urinary antigen
19Warning Tropical northern Australia: melioidosis risk changes the beta-lactam
Wet season, or diabetes, hazardous alcohol use, CKD or chronic lung disease
- Ceftriaxone does not reliably treat melioidosis (Burkholderia pseudomallei)
- Use meropenem 1 g IV 8-hourly instead of ceftriaxone; keep azithromycin
- Seek ID advice; eTG tropical regimens also cover Acinetobacter
20Action Severe CAP: beta-lactam plus macrolide (or plus fluoroquinolone)
Adult doses. Tropical north with melioidosis risk: meropenem instead of ceftriaxone
- Ceftriaxone 1-2 g IV daily (or cefotaxime 1-2 g IV 8-hourly) PLUS azithromycin 500 mg IV daily
- OR beta-lactam PLUS moxifloxacin 400 mg daily or levofloxacin 750 mg daily
- Influenza positive: oseltamivir 75 mg orally 12-hourly for 5 days (adult; lower dose if CrCl 60 mL/min or less)
- Positive respiratory virus test: still give antibacterials
21Action Severe CAP without influenza: consider hydrocortisone
ATS 2025 suggests corticosteroids for severe CAP; not for influenza pneumonia
- Hydrocortisone 200 mg IV daily for 4 or 7 days (by clinical improvement), then taper; total 8 or 14 days
- Do not give for influenza pneumonia or nonsevere CAP
- Monitor blood glucose
- Path rejoins step 16Shared downstream outcome
Guideline Source
Diagnosis and Management of Community-acquired Pneumonia: An Official ATS Clinical Practice Guideline (Jones et al., AJRCCM 2026;212(1):24-44); antibiotic regimens per ATS/IDSA 2019 (Metlay et al.)
Clinical Safety Information
Clinical Decision Support — Not a Substitute for Clinical Judgment
Individual patient factors may require deviation from these recommendations.
Known Limitations
- Immunocompetent adults only; not for children, immunocompromised patients, or hospital-acquired or ventilator-associated pneumonia
- Australia: eTG Antibiotic regimens differ and take precedence; in tropical northern Australia cover melioidosis in severe CAP
- Antibiotic choice should follow local resistance data and antibiograms
- Doses are for adults with normal renal function; adjust for renal impairment
Contraindicated Populations
Children (under 18 years)Immunocompromised patients (chemotherapy, transplant, advanced HIV, neutropenia)Pregnancy: doxycycline and fluoroquinolone options not suitableHospital-acquired or ventilator-associated pneumonia
Applicable Regions
USEUAUInternational
AU: Follow Therapeutic Guidelines (eTG) Antibiotic for CAP regimens and SMART-COP for severity. Ampicillin-sulbactam and levofloxacin are not marketed in Australia. Tropical northern Australia: meropenem instead of ceftriaxone for severe CAP with melioidosis risk; seek ID advice.
EU: National guidance (for example ERS/ESCMID) may prefer penicillin-based regimens.
US: ATS 2025 recommendations with ATS/IDSA 2019 regimens. Azithromycin monotherapy only where pneumococcal macrolide resistance is under 25%.
International: Adapt empiric cover to local pathogen epidemiology and resistance.
Version 2Next review: 2027-09-30
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Related Resources
Frequently Asked Questions
What is the Community-Acquired Pneumonia Management (ATS 2025)?
The Community-Acquired Pneumonia Management (ATS 2025) is a management clinical algorithm for Infectious Disease. It provides a structured decision tree to guide clinical decision-making, based on Diagnosis and Management of Community-acquired Pneumonia: An Official ATS Clinical Practice Guideline (Jones et al., AJRCCM 2026;212(1):24-44); antibiotic regimens per ATS/IDSA 2019 (Metlay et al.).
What guideline is the Community-Acquired Pneumonia Management (ATS 2025) based on?
This algorithm is based on Diagnosis and Management of Community-acquired Pneumonia: An Official ATS Clinical Practice Guideline (Jones et al., AJRCCM 2026;212(1):24-44); antibiotic regimens per ATS/IDSA 2019 (Metlay et al.) (DOI: 10.1164/rccm.202507-1692ST).
What are the limitations of the Community-Acquired Pneumonia Management (ATS 2025)?
Known limitations include: Immunocompetent adults only; not for children, immunocompromised patients, or hospital-acquired or ventilator-associated pneumonia; Australia: eTG Antibiotic regimens differ and take precedence; in tropical northern Australia cover melioidosis in severe CAP; Antibiotic choice should follow local resistance data and antibiograms; Doses are for adults with normal renal function; adjust for renal impairment. Individual patient factors may require deviation from these recommendations.
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