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Community-acquired pneumonia in children
Age predicts the pathogen: most preschool pneumonia is viral and S. pneumoniae is the leading bacterium, Mycoplasma rises from age 5, and the first-line bacterial treatment in an immunised child is high-dose amoxicillin.
Why it matters in the exam
The question builds a child with fever, cough and tachypnoea and asks for the likely pathogen by age, whether a chest X-ray is needed, whether to admit and which antibiotic to give. In an afebrile infant aged 1–3 months with a staccato cough, conjunctivitis and eosinophilia the answer is Chlamydia trachomatis, and in an adolescent with a long dry cough and low-grade fever the answer is Mycoplasma.
The second exam point is the drug choice. An immunised child treated at home receives amoxicillin 90 mg/kg per day in two doses; macrolides are kept for a suspected atypical pathogen. An immunised child who is admitted receives ampicillin, and a third-generation cephalosporin is kept for the unimmunised child, severe disease or areas with high resistance.
Remember the complications too: parapneumonic effusion and empyema (S. pneumoniae, S. aureus and group A streptococcus), pneumatoceles pointing to S. aureus, and the "round pneumonia" of the young child that looks like a mass and does not justify a tumour work-up. A child who does not improve within 48–72 hours of appropriate treatment needs reassessment and a repeat image to look for effusion or abscess.
Key points
- Most preschool pneumonia is viral; the leading bacterium is S. pneumoniae.
- From age 5, Mycoplasma is common and is treated with azithromycin.
- Home treatment in an immunised child: amoxicillin 90 mg/kg per day in two doses.
- Admission: hypoxaemia below 90%, distress, dehydration, toxic appearance or very young age.
- No improvement within 48–72 hours → look for effusion, empyema or abscess.
Summary table
| Age | Leading pathogen | Clinical clue | Empirical treatment |
|---|---|---|---|
| Newborn (up to 3 weeks) | GBS, Gram-negative bacilli, Listeria | Part of the neonatal sepsis picture | Ampicillin plus gentamicin in hospital |
| 3 weeks to 3 months, afebrile | Chlamydia trachomatis | Staccato cough, conjunctivitis, eosinophilia | Azithromycin |
| 3 months to 5 years | Viruses (RSV, hMPV and others); leading bacterium S. pneumoniae | High fever and lobar consolidation when bacterial | Amoxicillin 90 mg/kg per day in two doses |
| 5 years and older | Mycoplasma pneumoniae, S. pneumoniae | Long dry cough, headache, subtle bilateral findings | Azithromycin if atypical; amoxicillin if pneumococcal |
| Any age, complicated disease | S. aureus (including MRSA), group A streptococcus | Empyema, pneumatoceles, toxic appearance | Ceftriaxone plus vancomycin or clindamycin according to severity |
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Sources
- IDSA/PIDS Clinical Practice Guideline: Management of Community-Acquired Pneumonia in Infants and Children Older Than 3 Months, 2011 — Antimicrobial therapy and site-of-care decisions
- Nelson Textbook of Pediatrics, 22nd edition (2024) — Community-Acquired Pneumonia
- WHO Pocket Book of Hospital Care for Children, 2nd edition (2013) — Cough or difficult breathing
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.