In pneumonia with poultry exposure, which organism is most likely?

• A. Mycoplasma pneumoniae
• B. Viral pneumoniae
• C. Pneumococcal
• D. Chlamydia pneumoniae

Answer: (D)

Exposure to poultry points to psittacosis, an atypical pneumonia caused by Chlamydophila psittaci. This organism is an intracellular bacterium transmitted through inhalation of dust from dried bird droppings and secretions, commonly associated with poultry and pet birds. The illness often presents with fever, headache, myalgias, and a dry cough, with chest imaging showing patchy interstitial or focal consolidation rather than a classic lobar pattern. Diagnosis is typically made by serology or PCR. Treatment responds well to doxycycline (or other tetracyclines/macrolides if needed). This bird-borne pattern helps distinguish it from pneumococcal pneumonia (which is more abrupt with productive cough and lobar consolidation) and from Mycoplasma or Chlamydia pneumoniae infections, which lack the strong bird exposure link.