Study of a Clostridium Difficile Toxoid Vaccine (ACAM-CDIFF™) in Subjects With Clostridium Difficile Infection

Primary objective: To compare the event rate of CDI in groups assigned to ACAM-CDIFF™ vaccine versus placebo in the 9 week period after the third dose of the study vaccine in subjects with first episode of CDI receiving antibiotics standard of care. Secondary objective: To evaluate the safety of all dose groups of ACAM-CDIFF™ vaccine versus placebo in subjects with first episode of CDI receiving antibiotics standard of care.