Approximately 65 patients will be entered into this study taking place in North America. The aim of this study is to evaluate the safety, efficacy and absorption of an investigational drug in patients with C. difficile-associated diarrhea (CDAD). All study related care is provided including doctor visits, physical exams, laboratory tests and study medication. Total length of participation is 6 weeks.

Inclusion Criteria:

• The presence of CDAD at the time of enrollment
• Negative serum pregnancy test (HCG) for women of childbearing potential.

Exclusion Criteria:

• Any contraindication to oral / enteral therapy including fulminant C. difficile disease.
• Any acutely life-threatening medical conditions.
• Acute or chronic diarrhea of other cause.