Frontline therapy for Chlamydia pneumoniae (pneumonia) is which antibiotic?

• A. Azithromycin
• B. Doxycycline
• C. Levofloxacin
• D. Augmentin

Answer: (B)

Chlamydia pneumoniae is an intracellular atypical pathogen, so the most effective treatments are antibiotics that penetrate cells and inhibit bacterial protein synthesis. Doxycycline, a tetracycline, achieves strong intracellular concentrations and reliably covers atypical organisms like Chlamydia, making it the frontline option. While macrolides (like azithromycin) and fluoroquinolones (like levofloxacin) can also treat this infection, doxycycline is typically preferred due to its potency and tolerability in this context. Amoxicillin-clavulanate is not effective against intracellular pathogens such as Chlamydia, so it isn’t used as frontline therapy.