A 25-year-old, non-pregnant female presents with gray-white vaginal secretions and a fishy odor; a KOH prep reveals clue cells. The treatment of choice is which medication?

• A. Azithromycin (Zithromax).
• B. Metronidazole (Flagyl).
• C. Ceftriaxone (Rocephin).
• D. Miconazole (Monistat, Lotrimin).

Answer: (B)

This presentation points to bacterial vaginosis, an overgrowth of anaerobic bacteria such as Gardnerella vaginalis. The clue cells on microscopy and the fishy odor with gray-white discharge are characteristic. The treatment of choice is metronidazole because it is highly effective against anaerobes that drive BV. A common regimen is oral metronidazole 500 mg twice daily for 7 days (alternatively, metronidazole vaginal gel 0.75% applied intravaginally for several days). It’s important to avoid alcohol during treatment and for 24 hours after the last dose to prevent a disulfiram-like reaction. The other medications listed target different infections (yeast, gonorrhea, or chlamydia) and are not appropriate for BV.