What is the treatment of choice for Chlamydia psittaci in humans?

• A. Tetracyclines
• B. Macrolides
• C. Fluoroquinolones
• D. Penicillins

Answer: (A)

Chlamydia psittaci is an intracellular organism, so the treatment that reliably reaches and acts inside host cells is needed. A tetracycline, typically doxycycline, is preferred because it penetrates tissues and cells well and inhibits bacterial protein synthesis effectively in intracellular Chlamydia. Macrolides can be used if tetracyclines are not suitable (for example, in pregnancy or young children), but they aren’t as consistently effective for psittacosis as doxycycline. Fluoroquinolones and penicillins are not first-line because they’re less reliable against intracellular Chlamydia. So the best choice is a tetracycline.