Antibiotic-associated hemorrhagic colitis.

Antibiotic-associated hemorrhagic colitis is an infrequently recognized, self-limited process that may be experienced by patients receiving oral penicillin derivatives, primarily for upper respiratory infections. Symptoms of diarrhea, abdominal tenderness, and ultimately bloody diarrhea occur within one week of antibiotic use. Resolution of symptoms typically occurs within three days of discontinuing the offending antibiotic. Previous reports have suggested a non-inflammatory process involving the right colon. We present four cases and review the literature with respect to presentation, diagnosis, course, and postulated pathophysiologic mechanisms. Our patients demonstrate a more heterogeneous population than previously noted. This disease can affect young and old, male and female, and can involve the entire colon. Active inflammation demonstrated by fecal leukocytes, peripheral leukocytosis, and an active inflammatory infiltrate on biopsy are reported.