A 28-year-old woman with lower abdominal pain, fever, and vaginal discharge; recent unprotected sexual intercourse and a history of chlamydia one year ago; which antibiotic is most appropriate?

• A. Ciprofloxacin
• B. Metronidazole
• C. Azithromycin
• D. Doxycycline

Answer: (C)

The key idea is treating a likely Chlamydia trachomatis infection in a sexually active young woman who may have pelvic inflammatory disease. Azithromycin is a good choice here because it reliably covers Chlamydia and comes in a convenient single-dose regimen (a one-time high dose). This makes it easier for a patient to complete therapy, which is important to prevent ongoing transmission and complications.

Ciprofloxacin is less appropriate because fluoroquinolones have poorer activity against Chlamydia and resistance concerns limit their use for this infection. Metronidazole targets anaerobes and organisms like bacterial vaginosis and trichomonas, but it does not reliably treat Chlamydia. Doxycycline is also effective against Chlamydia and is commonly used, especially as part of PID treatment, but in this scenario the single-dose azithromycin option offers the strongest combination of coverage for Chlamydia with greater adherence potential.