Clostridium difficile are bacteria that are naturally found within the body.  After antibiotic use, such as ampicillin and clindamycin, much of the natural flora is suppressed and C. difficile proliferates.  If overgrown, it can cause pseudomembranous colitis, a severe infection of the colon.  The bacteria excrete toxins that cause bloating, constipation, abdominal pain and diarrhea with the presence of blood and mucus.  Once detected, the antibiotics that caused colitis are stopped and anticlostridial antibiotics are started.