- Diarrhea caused by a known gastrointestinal disorder such as idiopathic ulcerative colitis, Crohn's disease, acute stool culture positive bacterial colitis (documented within the last 2 weeks prior to study entry AND not having at least 2 weeks of antibiotic therapy), pseudomembranous colitis (Clostridium difficile toxin positive), short gut syndrome, chronic pancreatitis (alcoholic or idiopathic), ischemic bowel disease, or enteroenteric fistulae.