First-line treatment for uncomplicated Chlamydia trachomatis urethritis?

• A. Azithromycin 1 g single dose
• B. Ceftriaxone 250 mg IM
• C. Metronidazole 500 mg bid
• D. Doxycycline 100 mg BID x 7 days

Answer: (D)

Chlamydia trachomatis urethritis is best treated with doxycycline because this intracellular bacterium responds best to a regimen that maintains effective drug levels over several days. Doxycycline 100 mg taken orally twice daily for 7 days provides sustained intracellular exposure, leading to higher cure rates for urogenital chlamydial infections than a single-dose antibiotic. An alternative option, azithromycin given as a single 1 g dose, is acceptable in some situations but generally has lower and less consistent efficacy in many patient populations, so it is not preferred as the first-line choice. Metronidazole targets anaerobes and Trichomonas, not Chlamydia, and ceftriaxone is used for gonorrhea, not uncomplicated chlamydial urethritis.