Prevention of Clostridium Difficile-associated Diarrhea by Daily Intake of Kefir

Inclusion Criteria: Patients who have: * Been admitted to the medical unit on 7 West at St. Luke's Hospital (Duluth, MN) * Been prescribed a systemic antibiotic of any kind (administered by oral or parenteral route), but have not yet started the regimen * Consented to be randomized and take part in the study and are adults greater than 19 years of age Exclusion Criteria: Patients who are/have: * Tube feeding * Undergoing dialysis and other renal treatment * An existing C. difficile infection * A recent history of C. difficile infection (within the last 3 months) * A recent history of antibiotic use (within the last 3 months) * Inflammatory bowel disease, Crohn's disease, or other chronic gastrointestinal syndrome * A history of acquired of genetic immunodeficiencies; active, acute or chronic serious infections (i.e., viral hepatitis, HIV/AIDS), or autoimmune disorders * Undergoing gastrointestinal surgery, radiation, or cytotoxic chemotherapy * Allergy to milk protein