5.1. Pneumonia (CAP & HAP)

📄 Definition

Pneumonia is an acute infection of the lung parenchyma causing consolidation, typically with cough, fever, and breathlessness.

Types include:

  • CAP – Community-Acquired Pneumonia

  • HAP – Hospital-Acquired Pneumonia (onset ≥48 hours after admission)

Mnemonic: LUNG INFECTION
Lobar or Unilateral
New infiltrates on imaging
Green/yellow sputum
Infection signs (fever, ↑CRP)
Neutrophilia
Fatigue
Elevated RR
Confusion (elderly)
Tachycardia
Inspiratory crackles
Overexertion breathlessness
Night sweats ± pleuritic pain

Pathophysiology

  • Inhalation of microbes (e.g. Streptococcus pneumoniae)
    → alveolar inflammation
    → capillary leak + exudate
    → consolidation and impaired gas exchange

Risk Factors

Mnemonic: SPLASH
Smoking
Pre-existing lung disease (COPD, asthma)
Low immunity (HIV, diabetes, cancer)
Age extremes (elderly, infants)
Steroids or immunosuppressants
Hospitalisation (for HAP)

🤒Clinical Features

Mnemonic: COPS
Cough (productive ± blood-streaked)
Over 38°C fever
Pleuritic chest pain
Shortness of breath

Others: rigors, confusion (elderly), fatigue

Diagnosis

  • CXR = gold standard

  • FBC: neutrophilia

  • CRP, U&Es (for CRB65)

  • Blood cultures (if severe)

  • Sputum culture ± Legionella/pneumococcal urinary antigens

  • O₂ sats (ABG if <92%)

CXR Findings

Mnemonic: ABC of Consolidation
Air bronchograms
Bronchial wall thickening
Confluent opacity (lobar or patchy)

Lobar: homogeneous, sharp borders
Bronchopneumonia: multifocal, patchy
Aspiration: often lower zone, right lung

Severity Assessment – CRB65 Score (NICE)

Mnemonic: CRB65
Confusion (AMTS ≤8)
Respiratory rate ≥30
Blood pressure (SBP <90 or DBP ≤60)
65 years or older

ScoreRiskAction
0LowHome treatment ± PO antibiotics
1–2ModerateHospital referral
≥3HighUrgent hospital admission ± ITU review

Management

➤ CAP

Mnemonic: CAP DOC
CURB65 score guides location of care
Amoxicillin 500 mg TDS 5 days (mild)
Penicillin allergy → doxycycline or clarithromycin
Dual therapy (amoxicillin + macrolide) if moderate/severe
Oxygen + fluids if needed
CXR repeat in 6 weeks if red flags (e.g. smoker, >50yrs)

➤ HAP

  • Within 5 days: cover Gram-positive + typicals

  • After 5 days: cover Gram-negative + resistant bugs
    e.g. co-amoxiclav or piperacillin-tazobactam

Monitoring & Follow-Up

  • O₂ sats, RR, temp, HR

  • Check CRP, WCC, and U&Es

  • Repeat CXR after 6 weeks if:
    smoker
    >50 yrs
    slow resolution
    lobar consolidation

Complications

Mnemonic: LIES
Lung abscess
Infection spread (empyema, sepsis)
Effusion (parapneumonic or empyema)
Scarred lung (fibrosis, bronchiectasis)

Differential Diagnoses

Mnemonic: PALM PECS
Pulmonary embolism
Asthma/COPD exacerbation
Lung cancer
Myocardial infarction
Pleural effusion
Eosinophilic pneumonia
COVID-19
Sarcoidosis

Last updated in line with NICE NG138 (October 2019)
Reviewed for PassMap: 14 July 2025
This content is NICE-compliant and exam-optimised for the Physician Associate Regulation Assessment (PARA).

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