Metronidazole is most effective against which type of organisms?

Metronidazole is most effective against which type of organisms?

• A. Aerobic microorganisms
• B. Microaerophilic microorganisms
• C. Obligate anaerobic microorganisms
• D. Obligate intracellular microorganisms

Answer: (C)

Metronidazole is activated only in low-oxygen environments. In obligate anaerobic organisms, bacterial nitroreductases reduce the nitro group on metronidazole to reactive intermediates that damage DNA and other critical macromolecules, leading to cell death. Oxygen presence interferes with this reduction, so the drug is much less active in aerobic or highly oxygenated conditions. Because of this activation specificity, metronidazole is most effective against obligate anaerobic microorganisms. It is far less effective against aerobic bacteria, microaerophiles, or obligate intracellular pathogens, where activation is limited or not achieved.

Metronidazole is activated only in low-oxygen environments. In obligate anaerobic organisms, bacterial nitroreductases reduce the nitro group on metronidazole to reactive intermediates that damage DNA and other critical macromolecules, leading to cell death. Oxygen presence interferes with this reduction, so the drug is much less active in aerobic or highly oxygenated conditions. Because of this activation specificity, metronidazole is most effective against obligate anaerobic microorganisms. It is far less effective against aerobic bacteria, microaerophiles, or obligate intracellular pathogens, where activation is limited or not achieved.