Although most cases of CDI can be treated successfully with relatively safe and effective oral antibiotics (i.e., metronidazole or vancomycin), primary prevention of CDI is critical because up to one in five treated patients endures a relapse or reinfection, which can be difficult to treat; infected patients serve as a reservoir for ongoing transmission within facilities; implementation of contact isolation precautions for patients who have CDI can have deleterious consequences for the patient; and, CDI can result in death or severe disease including those treated by colectomy. Because CDI is spread between patients, prevention of a single case should reduce the risk of exposure for other hospital patients.