Chlamydophila psittaci
Summary
Chlamydophila psittaci is an obligate intracellular bacterium acquired from birds, especially parrots and parakeets, that causes psittacosis, an atypical pneumonia. Exposure history to birds is the diagnostic clue.
Detail
Like all chlamydiae it has a biphasic life cycle: the metabolically inert elementary body is the infectious form that enters the cell, converts to the replicating reticulate body within an inclusion, and then reconverts and is released. It cannot make its own ATP and so is an energy parasite, and its cell wall lacks classic muramic acid, which is why beta-lactams are ineffective. Transmission is by inhaling aerosolized dried droppings or respiratory secretions of infected psittacine birds, turkeys, and pigeons; person-to-person spread is negligible. Psittacosis presents with abrupt high fever, severe headache, and a dry cough, with chest findings that are strikingly milder than the radiographic infiltrates, the classic mismatch of atypical pneumonia. Relative bradycardia, splenomegaly, and a rash (Horder spots) may occur, and hepatitis is common. Doxycycline is the treatment of choice, with macrolides as an alternative. Occupational risk falls on pet shop workers, veterinarians, and poultry processors.
Sources
- Levinson Medical Microbiology and Immunology
- Harrison's Principles of Internal Medicine
Reviewed by AnkiBoss editorial — medical student review. Information here is for study reference only and is not medical advice. Spotted an error? Let us know.