Antibiotic-associated colitis.

We determined the incidence of antibiotic-associated colitis among users of oral antibiotics or topical clindamycin in a large prepaid health plan. Exposure to antibiotics was determined using a system that automatically records outpatient prescriptions filled and hospital diagnoses were available from computer files. Four cases of acute colitis were judged likely to be causally linked with outpatient use of antibiotics. These findings provide substantial evidence that antibiotic-associated colitis requiring hospital treatment occurs very rarely.