colitis, pseudomembranous Severe inflammation of the inner lining of the colon, usually due to the Clostridium difficile bacterium. Patients taking antibiotics are at particular risk of becoming infected with C. difficile because the natural bacteria of the bowel can usually prevent proliferation of C. difficile, but they are disrupted by antibiotics. A toxin produced by C. difficile causes colitis symptoms, including diarrhea, abdominal pain, and severe inflammation. Rarely, the walls of the colon wear away and holes develop (colon perforation), which can lead to a life-threatening infection of the abdomen. See also Clostridium difficile.
