Which drug is a macrolide commonly used to treat Chlamydia infections?

• A. Doxycycline
• B. Azithromycin
• C. Amoxicillin
• D. Erythromycin

Answer: (B)

Macrolides work by binding to the 50S ribosomal subunit, blocking protein synthesis, and they’re active against Chlamydia. Among macrolides, azithromycin is the drug most commonly used for Chlamydia because it reaches good intracellular levels and can be given as a single, convenient dose. That single-dose approach helps ensure patients complete treatment, which is especially important for sexually transmitted infections.

Doxycycline is also effective against Chlamydia but is not a macrolide; it’s a tetracycline and has pregnancy and young-child restrictions. Amoxicillin is a beta-lactam antibiotic, not a macrolide. Erythromycin is an older macrolide but tends to have more gastrointestinal side effects and less favorable dosing and tolerability compared with azithromycin, making azithromycin the preferred choice for uncomplicated Chlamydia infections.