A 55-year-old man who recently returned from a hotel conference develops high fever, dry cough, breathlessness, watery diarrhoea and confusion. He is a heavy drinker. Chest radiograph shows lobar consolidation. Serum sodium is 126 mEq/L, AST mildly raised. Urinary antigen testing confirms the organism. Which antibiotic is the drug of choice?
- A Amoxicillin-clavulanate
- B Levofloxacin ✓
- C Ceftriaxone
- D Benzylpenicillin
Correct answer: B. Levofloxacin
Explanation
Legionella pneumophila classically causes severe CAP with gastrointestinal symptoms, hyponatraemia, deranged liver enzymes and relative bradycardia, often linked to contaminated water systems. It is an intracellular organism, so beta-lactams are ineffective regardless of dose; treatment requires intracellular penetration with a macrolide or a respiratory fluoroquinolone such as levofloxacin. Amoxicillin-clavulanate, ceftriaxone and penicillin all fail against intracellular pathogens, which is the fact that kills these distractors.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.