02.02 Resp

02.02 Respiratory [PDF link]: Pneumonia: Community acquired (CAP), Hospital-acquired (HAP), Atypical pneumonia (Legionella, Chlamydia psittaci, Mycoplasma pneumoniae, Chlamydophillia pneumoniae, Q fever, Coxiella burnetti), Pneumonia in immunocompromised patients – Pneumocystic jirovecii (PCP), Aspergillosis, Lung abscess / empyema, Aspiration pneumonia, Acute bronchitis

External links

• CURB-65 score for pneumonia: MDCalc

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More on pneumonia

• NICE guidelines NG250, published Sep 2025 – covers both CAP & HAP

Hints about potential aetiology of pneumonia

• Hx of alcohol use + cavitation on CXR: Klebsiella pneumoniae

• Hx of prior flu: Staph aureus

• A/w chicken pox: Varicella pneumonitis

• Hemolytic anaemia = Mycoplasma pneumoniae

  • Cold agglutinin disease. Gabbard AP, Booth GS. Cold Agglutinin Disease. Clin Hematol Int 2020;2:95–100. https://doi.org/10.2991/chi.k.200706.001.

• A/w erythema multiforme ± mucositis – think M. pneumoniae

  • Article with some good images – Lu H, Zhang B. Mycoplasma-Induced Rash and Mucositis. N Engl J Med 2023;389:1601–1601. https://doi.org/10.1056/NEJMicm2305301.

  • Another article with pictures of more severe mucositis – Li T, Lee N. Mycoplasma pneumoniae –Associated Mucositis. N Engl J Med 2018;379:1262–1262. https://doi.org/10.1056/NEJMicm1614484.

• A/w hyponatraemia ± travel history = Legionella

• After seizures, loss of consciousness, feeding at risk, etc – think aspiration pneumonia

• HSV oral lesions = Strep pneumoniae

• Parrots involved = Chlamydia psittaci

• Farm animals (esp in endemic region) – ? Q fever (Coxiella brunetti)

• PMH of HIV + desaturation on exertion = Pneumocystis jirovecii (aka PCP)

• PMH of cystic fibrosis = Consider Pseudomonas or Burkholderia

  • Some patients will have chronic / recurrent infections

• PMH of COPD = Haemophilus influenzae

• Most common cause of CAP in general is still Strep pneumoniae