What is a standard first-line treatment for uncomplicated chlamydial infection?

• A. Doxycycline 100 mg twice daily for 7 days
• B. Azithromycin 1 g single dose
• C. Ceftriaxone 250 mg IM
• D. Levofloxacin 500 mg daily for 7 days

Answer: (A)

Uncomplicated Chlamydia trachomatis infection is best treated with doxycycline 100 mg taken orally twice daily for 7 days because this regimen achieves sustained intracellular exposure and yields high microbiologic cure rates. The intracellular nature of Chlamydia means the antibiotic needs to be present over several days to fully eradicate the organism residing inside host cells, which is why a 7-day course is preferred. An alternative single-dose azithromycin (1 g) is acceptable if adherence to a 7-day course is unlikely, but it can have slightly lower cure rates in some settings. Ceftriaxone is used for gonorrhea and is not sufficient by itself for chlamydia, and fluoroquinolones like levofloxacin are avoided due to resistance concerns and safety considerations. Therefore, doxycycline for a week is the best first-line choice.