A 45-year-old poultry farm worker presents with 10 days of fever, severe headache, dry cough, and patchy consolidation on chest X-ray. Examination reveals splenomegaly. He keeps several pet parrots at home. Which organism is the most likely cause?
- A Mycoplasma pneumoniae
- B Chlamydophila pneumoniae
- C Chlamydophila psittaci ✓
- D Legionella pneumophila
Correct answer: C. Chlamydophila psittaci
Explanation
Psittacosis is caused by Chlamydophila psittaci and follows exposure to infected birds, classically parrots and other psittacines but also poultry. It presents as an atypical pneumonia with prominent systemic features, and relative bradycardia and splenomegaly are recognised clues. Chlamydophila pneumoniae causes a milder atypical pneumonia with no avian link, and Mycoplasma pneumoniae spreads person to person among close contacts. The occupational and pet bird exposure is the discriminating detail here.
Reference: Jawetz, Melnick and Adelberg's Medical Microbiology, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.