Which statements about Metronidazole are correct?

• A. I only
• B. I and IV
• C. I II
• D. I III IV

Answer: (D)

Metronidazole works best in anaerobic environments because it is reduced inside anaerobic cells to reactive intermediates that damage DNA. This activation step is inhibited by oxygen, so the drug is effective against anaerobic bacteria and certain protozoa, but not against aerobic bacteria. That key idea explains why statements about its activity are typically correct when they emphasize anaerobes and DNA damage, and why statements claiming it works against aerobes are incorrect.

Clinically, it’s used for infections involving anaerobes (like many intra‑abdominal and gynecologic infections), as well as certain protozoal infections (such as Giardia, Entamoeba, and Trichomonas). Common side effects include nausea, a metallic taste, and dark urine; it can cause a disulfiram‑like reaction with alcohol, and it can interact with other drugs (notably warfarin), affecting bleeding risk or metabolism. Prolonged use can lead to neuropathy.

So the correct statements would align with its anaerobic spectrum, its mechanism of DNA damage via reduction, its alcohol interaction, and its drug interactions, while any statement claiming it’s effective against aerobic bacteria or omitting known interactions would be incorrect.