Metronidazole Mechanism — NDEB AFK MCQ
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Correct answer: E — Production of cytotoxic free radicals that damage bacterial DNA under anaerobic conditions
Metronidazole is a nitroimidazole antimicrobial that is selectively toxic to anaerobic organisms. Under anaerobic conditions, the nitro group is reduced to cytotoxic intermediates that damage DNA, causing strand breakage and cell death. It is effective against obligate anaerobes (Bacteroides, Fusobacterium, Porphyromonas, Prevotella, Treponema, Clostridium) but ineffective against aerobes and facultative anaerobes. It is often combined with amoxicillin for mixed aerobic-anaerobic dental infections.
Reference: Katzung – Basic and Clinical Pharmacology, 15th ed., 2021