Bacteroides fragilis meningitis.

Bacteroides fragilis is an obligate anaerobic bacillus residing in the normal intestinal flora of the colon. Anaerobic bacterial meningitis due to this pathogen is rarely diagnosed and if present, a predisposing source of infection should be actively sought for. Anaerobic cultures of cerebrospinal fluids should be done for patients with meningitis, especially those with concomitant pathologies that predispose to anaerobic infections. Two cases of anaerobic meningitis due to Bacteroides fragilis, one associated with cholesteotoma and the other with nasopharyngeal carcinoma, are reported. Both were successfully treated with metronidazole.