Metronidazole treatment of Bacteroides fragilis infections

Seven patients with Bacteroides fragilis infections were treated with intravenous and/or oral metronidazole. Infections treated included endocarditis, osteomyelitis, lung abscess, empyema, peritonitis, septicemia, and pelvic infection. Some patients had failed to respond to therapy with chloramphenicol or clindamycin or both. Metronidazole was used alone or in combination with aminoglycosides. Serum levels of metronidazole several times in excess of the minimal inhibitory concentrations for the organisms were easily achieved and in one patient the CSF metronidazole level was equal to that of the serum. Response to therapy with metronidazole was considered to be excellent. The only serious side effect noted was hypotension, which occurred in the last patient. Therapy was discontinued, and therefore therapeutic results could not be evaluated. Metronidazole appears to be a safe and effective agent in the treatment of B fragilis infections.