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Legionella pneumonia — SCE Respiratory MCQ

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ModerateRespiratory InfectionsLegionella pneumoniaSCE Respiratory

A 55-year-old hotel maintenance worker presents with fever, dry cough, diarrhoea and confusion. Sodium is 124 mmol/L, LFTs are mildly deranged and CXR shows bilateral patchy consolidation. Several colleagues have a similar illness after a cooling-system fault. What is the most likely diagnosis?

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Correct answer: A — Legionella pneumonia

Severe atypical pneumonia with diarrhoea, hyponatraemia, deranged LFTs and a water-system exposure strongly suggests Legionella. Mycoplasma can be atypical but is less associated with marked hyponatraemia and outbreak water exposure. Pneumococcus, TB and Pneumocystis have different tempo, risk factors and systemic clues.

Reference: BTS CAP Guideline; NICE pneumonia antimicrobial guidance