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Community-acquired pneumonia (CAP)
A severity score (CURB-65 or PSI) sets the site of care, the site of care and comorbidities set the antibiotic, and clinical stability rather than a fixed number sets the duration (usually 5 days).
Why it matters in the exam
Almost every question starts with a patient with fever, cough and an infiltrate on the chest film and asks whether to admit and which antibiotic to give. The five parts of CURB-65 and what each score means must therefore be known, as must the difference between a healthy young adult (amoxicillin) and a patient with comorbidities (a combination or a respiratory quinolone), and the hospital combination: a beta-lactam with a macrolide. Further questions test when to add cover for MRSA or Pseudomonas — only after a previous respiratory culture grew it, or after a hospital stay with intravenous antibiotics during the past 90 days.
Another set of questions identifies the organism from clues: Legionella with hyponatraemia, diarrhoea, high fever and a urinary antigen test; Mycoplasma in a young adult with features outside the lung; Staphylococcus aureus after influenza; Klebsiella in a person with alcohol use disorder and an upper-lobe infiltrate. The candidate should also know that a repeat film is not routinely needed once the patient improves, but in an older smoker or when symptoms persist a film after 6 weeks is advisable so as not to miss a tumour. In severe pneumonia the 2023 guidance allows hydrocortisone to be considered.
Key points
- CURB-65: confusion, urea, a breathing rate of 30 or faster, low blood pressure and age 65 or older.
- Score 0–1: treat at home; 2: think about admission; 3 and above: hospital, with intensive care in mind.
- Healthy young adult: amoxicillin; with comorbidities: a combination or a respiratory quinolone.
- On the ward: beta-lactam + macrolide; MRSA or Pseudomonas cover only with risk factors.
- Treat for at least 5 days and until clinically stable for 48 hours.
Summary table
| Setting | Preferred antibiotic | Alternative | Notes |
|---|---|---|---|
| Outpatient, no comorbidities | Amoxicillin 1 g three times a day | Doxycycline; a macrolide only if pneumococcal resistance is below 25% | Usually 5 days |
| Outpatient, with comorbidities | Amoxicillin-clavulanate or a cephalosporin + a macrolide or doxycycline | A respiratory quinolone (levofloxacin, moxifloxacin) alone | Comorbidities: heart, lung, kidney, liver, diabetes, alcohol, malignancy |
| Ward admission | Ceftriaxone or ampicillin-sulbactam + a macrolide | A respiratory quinolone alone | Blood and sputum cultures in selected cases |
| Severe CAP (intensive care) | Beta-lactam + macrolide | Beta-lactam + respiratory quinolone | Consider hydrocortisone (2023) |
| Risk factors for MRSA or Pseudomonas | Add vancomycin or linezolid; or piperacillin-tazobactam or cefepime | Guided by previous cultures | Only with a prior positive culture or hospital IV antibiotics in the past 90 days |
A free exam question
מה קובע מדד Pneumonia Severity Index ( PSI ?) (the question as examined, in Hebrew)
- א. במי יש לטפל באנטיקואגולציה מניעתית
- ב. במי יש לטפל באנטיקואגולציה מלאה
- ג. את מי מהחולים יש להנשים
- ד. מי מהחולים בסיכון תמותה נמוך
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Sources
- ATS/IDSA Guideline: Diagnosis and Treatment of Adults with Community-acquired Pneumonia, 2019 — Site-of-care decisions, empirical antibiotic therapy and duration
- ERS/ESICM/ESCMID/ALAT Guidelines for the management of severe community-acquired pneumonia, 2023 — Corticosteroids in severe CAP
- Harrison's Principles of Internal Medicine, 21st edition (2022) — Pneumonia
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.