🫁 Chapter 37: Community-Acquired Pneumonia (CAP)

Age-based aetiology · Severe CAP criteria · Empirical antibiotics (cephalosporin + macrolide) · MRSA coverage · Investigations (blood culture, CXR, PCR) · Non-responder evaluation · Parapneumonic effusion · PICU admission criteria

🔍 Core Concepts: Community-Acquired Pneumonia

📌 Aetiology by Age
Neonates: RSV, Group B Strep, E. coli. Infants: RSV, S. pneumoniae. Toddlers: RSV, S. pneumoniae, H. influenzae. School-aged: M. pneumoniae, S. pneumoniae. Adolescents: M. pneumoniae, S. pneumoniae, TB.
⚠️ Severe CAP Criteria
Major: invasive ventilation, fluid-refractory shock, need for NIPPV. Minor: tachypnoea, PaO2/FiO2 <250, multilobar infiltrates, altered mental status, PEWS >6. ≥1 major or ≥2 minor → PICU admission.
💊 Empirical Antibiotics
IV ceftriaxone or cefotaxime + add macrolide (azithromycin) if atypical suspected. Add vancomycin/clindamycin for suspected MRSA or severe S. aureus (necrotising, toxic shock).
📊 Investigations
Blood cultures (2 sets), CXR (not needed for mild outpatient), CRP/PCT, NP swab for viral PCR, sputum culture if able. CT or ultrasound for complicated effusion/empyema.
📉 Non-responder management
After 48-72h no improvement: repeat CXR, consider CT, bronchoscopy with BAL, thoracentesis if effusion. Escalate antibiotics, rule out resistant organisms, empyema, occult infection.
🏥 PICU Admission Indications
Impending respiratory failure (hypoxaemia/hypercapnia), need for ventilatory support, haemodynamic instability, altered mental status.

🩺 Stepwise Approach: Community-Acquired Pneumonia

1
Assess severity (PICU criteria)
Check work of breathing, SpO2, mental status, haemodynamics. Severe CAP: need for invasive/NIPPV, shock, PaO2/FiO2 <250, multilobar infiltrates, altered sensorium. Admit to PICU if ≥1 major or ≥2 minor criteria.
2
Empirical antibiotic therapy
IV ceftriaxone (50-100 mg/kg/day) or cefotaxime. Add azithromycin (10 mg/kg/day) if atypical suspected (M. pneumoniae, Legionella). Add vancomycin or clindamycin if MRSA risk (necrotising, skin abscess, severe sepsis).
3
Supportive care & monitoring
Oxygen to maintain SpO2 >92%. Hydration (IV/NG). Antipyretics. Chest physiotherapy not routinely needed. Monitor for respiratory deterioration, effusion.
4
Investigations
CXR (admission and if no improvement in 48-72h). Blood cultures, CBC, CRP/PCT. NP swab for viral PCR. Sputum culture if able. Pleural tap if effusion >1cm or loculated.
5
Non-responder evaluation (48-72h)
No improvement? Repeat CXR, consider CT chest, bronchoscopy with BAL, thoracentesis. Escalate antibiotics (add MRSA coverage, consider resistant organisms). Drain empyema if present.
6
Discharge criteria
Clinically improving, afebrile for 24-48h, haemodynamically stable, SpO2 ≥92% on room air, able to tolerate oral antibiotics and feeds. Total course 7-10 days (longer for MRSA/complicated).