Clostridium difficile infections are of great concern for hospitals nationwide and C. difficile remains the most common nosocomial infection in North America. The majority of patients with C. difficile infection respond to orally administered metronidazole or vancomycin, but 5-30% of patients go on to develop recurrent infection and diarrhea, despite antibiotic treatments. The idea that gut microbiota influence susceptibility and recovery from disease is becoming more widely reported. Disruption of normal bacterial flora in the gut during systemic antibiotic use has been attributed to the uncontrolled growth of bacteria that are otherwise suppressed such as C. difficile. Even after an antibiotic regimen has concluded, restoration of the normal gut microbiota is thought to be paramount to interrupting the cycle of C. difficile infection. The idea of reintroducing normal microbial flora to patients with recurrent C. difficile infections has been the foundation upon which the use of probiotic agents, including fecal transplants, has been introduced. The use of probiotics to treat antibiotic-associated diarrhea, and specifically C. difficile infections, has been studied and successes have been reported, and in particular by our group. The emerging idea, however, is that probiotic consumption can be used to prevent the onset of a C. difficile infection, which requires further study. Meta-analyses have been conducted on previously reported data and ultimately conclude that the use of probiotics is safe and effective. However, there remains a need for a focused and controlled study assessing the efficacy of kefir consumption on the incidence of C. difficile infections at St. Luke's Hospital in Duluth, MN, and CHI Creighton University Medical Center in Omaha, NE. The data collected from this study have the potential to change clinical practice at not only our institutions, but at any hospital or institution that has a population of patients undergoing systemic antibiotic treatment.