Risk factors for persistent C. difficile infection include age greater than 65 years, poor nutritional status, recent abdominal surgery, prolonged hospitalization and recent stay in the ICU. The purpose of this study is to determine if administering a daily regimen of kefir to at-risk patients can reduce the incidence of C. difficile infections. Because treatment for C. difficile infections is difficult and expensive, and recurrent infections are common, a way to prevent these infections is of great interest. A preventive measure that reduces the incidence of diarrhea and C. difficile infections will clearly improve patient health, and will have a multi-fold impact on how patients are cared for while in the hospital as well as post-discharge. There is potential for cost-saving, as well, in the form of the direct cost of antibiotic treatments and prolonged hospital stays. Additionally, the cost in time and effort to prevent the spread of these infections will be reduced, as well, all of which ultimately improve patient care.