Which drug active against parasitic infections is important for treating infections caused by anaerobic bacteria?

Which drug active against parasitic infections is important for treating infections caused by anaerobic bacteria?

• A. Rifampin
• B. Isoniazid
• C. Metronidazole
• D. Trimethoprim

Answer: (C)

Metronidazole is activated in anaerobic environments, so it becomes a potent agent specifically against organisms that thrive without oxygen—namely many anaerobic bacteria and several protozoa. Inside these anaerobic cells, metronidazole is reduced to reactive species that damage DNA, leading to cell death. This mechanism makes it the drug of choice for infections caused by anaerobic bacteria such as Bacteroides and Clostridium species, and for protozoal infections like giardiasis, amebiasis, and trichomoniasis. The other medications listed do not target anaerobes or protozoa as effectively: rifampin mainly inhibits RNA synthesis in certain bacteria (not focused on anaerobes); isoniazid is TB-specific; trimethoprim acts on folate synthesis and covers many other bacteria but is not the primary agent for anaerobic infections or the protist parasites listed. So metronidazole best fits the requirement of treating anaerobic bacterial infections and related parasitic infections. Alcohol should be avoided during and shortly after therapy due to a possible disulfiram-like reaction.

Metronidazole is activated in anaerobic environments, so it becomes a potent agent specifically against organisms that thrive without oxygen—namely many anaerobic bacteria and several protozoa. Inside these anaerobic cells, metronidazole is reduced to reactive species that damage DNA, leading to cell death. This mechanism makes it the drug of choice for infections caused by anaerobic bacteria such as Bacteroides and Clostridium species, and for protozoal infections like giardiasis, amebiasis, and trichomoniasis. The other medications listed do not target anaerobes or protozoa as effectively: rifampin mainly inhibits RNA synthesis in certain bacteria (not focused on anaerobes); isoniazid is TB-specific; trimethoprim acts on folate synthesis and covers many other bacteria but is not the primary agent for anaerobic infections or the protist parasites listed. So metronidazole best fits the requirement of treating anaerobic bacterial infections and related parasitic infections. Alcohol should be avoided during and shortly after therapy due to a possible disulfiram-like reaction.