Antibiotic-associated hemorrhagic colitis.

Pseudomembranous colitis arising from Clostridium difficile super-infection after treatment with various antibiotics is a well-defined portion of the pathological spectrum of antibiotic related bowel injury. We have observed two patients with hemorrhagic colitis associated with the use of penicillin derivatives. The colitis was characterized by predominant right-sided involvement, sparing of the rectum and distal colon, absence of pseudomembrane formation, and presence of marked hemorrhage in the lamina propria. Discontinuation of antibiotics resulted in prompt resolution. Early colonoscopic examination was essential in establishing the diagnosis. Follow-up examination at 9 days demonstrated complete histological and endoscopic resolution.