Oral Vancomycin Versus Probiotics Versus Placebo for Prevention of Clostridium Difficile Infection in Colonized Patients

Inclusion Criteria: * Adult patients of 18 years of age or older identified as asymptomatic carriers of C. difficile (i.e. not meeting case definition of C. difficile infection, see below) * Started on systemic (oral or intravenous) antibiotics for any (presumed) bacterial infection * Patient must have vitals (heart rate, blood pressure, temperature), estimated creatinine clearance (using the Chronic Kidney Disease Epidemiology equation (CKD-Epi)) and a complete blood count available within 24 hours of enrolment Exclusion Criteria: * On a course of systemic antibiotics that had been started more than 72 hours ago (as current evidence suggests that the earlier probiotics are started, the more efficacious they are) * Patient with C. difficile, i.e. presence of diarrhea (three or more loose or watery stools within 24 hours), or fevers or hypotension from C. difficile infection * Any patients with contra-indications to probiotics or vancomycin: * Immunosuppressed (primary or acquired immunodeficiency, including AIDS (defined as AIDS defining condition or cluster of differentiation 4 (CD4) nadir of \<200/ul), hematologic malignancies, long-term systemic corticosteroid treatment, active treatment with chemotherapeutic agents or biologicals, autoimmune diseases, nephrotic syndrome) * Structural heart disease (e.g. atrial septal defect, ventricular septal defect) * Gastroesophageal or compromised gut integrity (e.g. short gut syndrome, intestinal injury or dysfunction, inflammatory bowel diseases including current or past history of Crohn's disease and ulcerative colitis) * Patients on systemic aminoglycosides, ethacrynic acid, polymixin B, or colistin. * Prior or current hearing loss * Female patients with known pregnancy or who are planning to get pregnant, or who are breastfeeding * Patients with end-stage renal diseases defined as an estimated glomerular filtration rate of \<15ml/min, or absence of a current estimated creatinine clearance * History of an allergic reaction to one of the study drugs, or sensitivity to milk * Patients started on probiotics or oral vancomycin while in hospital