What is the mechanism of action of metronidazole?

Metronidazole functions by interacting with microbial ferredoxins, which leads to the production of cytotoxic intermediates. Once metronidazole is reduced by these ferredoxins, it forms reactive species that damage the DNA of anaerobic bacteria and protozoa. This process ultimately results in the inhibition of nucleic acid synthesis and cell death.

In contrast, the other options describe mechanisms of action for different classes of antibiotics. For example, the inhibition of DNA gyrase is characteristic of fluoroquinolones, while inhibition of dihydrofolate reductase is the mode of action for drugs like trimethoprim. Binding to penicillin-binding proteins is relevant to beta-lactam antibiotics, such as penicillins and cephalosporins, which disrupt cell wall synthesis. Understanding these mechanisms provides insight into how different antibiotics are utilized in treating infections caused by various pathogens.