A Trial to Compare Xifaxan to Vancomycin for the Treatment of Clostridium Difficile-Associated Diarrhea (CDAD)

Inclusion Criteria: * Subject is 18 years of age or older, has acute diarrhea and at least 1 other sign of enteric infection present, such as fever, nausea/loss of appetite, vomiting, severe abdominal pain or discomfort. * Subject has a positive Clostridium difficile stool toxin assay at screening Exclusion Criteria: * Subject has had a previous episode of clinically diagnosed Clostridium difficile within the past 6 months. * Subject has chronic diseases associated with diarrhea (e.g., inflammatory bowel disease or diarrhea predominant irritable bowel syndrome \[DIBS\]) * Subject has had any therapy with any agent administered for the treatment of Clostridium difficile prior to randomization.