antibioticsbooks

Nitroimidazoles
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Agents: metronidazole, tinidazole
Nitroimidazoles are around to clean up organisms
that the big drug classes—penicillins, cephalosporins,
fluoroquinolones, macrolides, etc.—for
the most part miss. Worried about gut anaerobes?
Metronidazole is there for you. Thinking about parasites
in your patient with diarrhea? Try metronidazole
or its newer cousin tinidazole, which has a
spectrum of activity similar to that of metronidazole
but is approved only for parasitic infections. And of
course, if you have gone overboard with the antibiotics
and your patient has C. difficile colitis, turn
to metronidazole. Just remember the limitations
of these drugs: they do not have adequate activity
against aerobic bacteria—staphylococci, streptococci,
E. coli, and such.
Mechanism of Action
Anaerobic bacteria and protozoa—but not aerobic
bacteria—activate a part of the metronidazole molecule
that forms free radicals, which are thought to
damage DNA and lead to cell death.