This study evaluates the efficacy of prophylaxis with oral vancomycin for preventing recurrent Clostridium difficile Infection (CDI) in patients who have experienced at least one CDI episode in the last 180 days and are receiving antibiotics for a non CDI condition. Participants will be randomized to receive either placebo or oral vancomycin in addition to their prescribed antibiotic therapy.

Many patients who have a CDI experience recurrent or relapsing symptoms. The investigators are studying whether vancomycin in low doses will help prevent further CDI episodes and how this therapy impacts patients' gastrointestinal microbiome and composition.

Patients with a history of past CDI who are receiving antibiotics for a non-CDI condition will be invited to participate. Approximately half of the participants will receive a low-dose capsule of vancomycin and half will receive a placebo. Participants will continue taking the vancomycin/placebo for 5 days after their prescribed antibiotics end.

Inclusion Criteria:

• Willing to provide informed consent.
• Willing to comply with all study procedures and be available for the duration of the study.
• Documented diagnosis of at least one CDI within the last 180 days with treatment completed.
• Currently receiving systemic antibiotics for a non-CDI condition with anticipated duration of no more than 2 weeks.
• Females of childbearing potential must have a negative pregnancy test prior to randomization and agree to use adequate contraception prior to randomization, for the duration of the study, and for 4 weeks following study completion.
• Have received no more than 72 hours of non-CDI antibiotics.

Exclusion Criteria:

• History of hypersensitivity or allergy to oral vancomycin.
• Current use of oral vancomycin
• Patients on concurrent treatment with metronidazole or tetracycline monotherapy for any indication
• Patients diagnosed with inflammatory bowel disorder (Crohn's disease), or bacterial gastrointestinal infection cause by agents other than C. difficile (e.g. Salmonella sp.), toxic megacolon and/or known small bowel ileus.
• Dysphagia (inability to swallow capsules) or unwilling to swallow capsules.
• Major gastrointestinal surgery within 3 months of enrollment (does not include appendectomy or cholecystectomy).
• Any history of total colectomy or bariatric surgery.
• Unable or unwilling to fulfill study requirements.
• Expected life expectancy < 6 months.
• Patients enrolled in another clinical trial with investigational drugs within 30 days prior to randomization.
• Women who are pregnant or breast-feeding.
• Any patient deemed not suitable for study participation at the discretion of the study investigator.
• Diarrhea (3 or more loose stools in a 24 hour period) at enrollment.