All hospitalized patients in the NorthShore system >18 years of age who are diagnosed with active CDI, defined as >3 diarrheal stools per day and a positive C. difficile PCR assay, will be evaluated for inclusion in the study. Hospitalized patients presenting with their first or greater relapse of CDI occurring between 15 and 90 days after an index episode of CDI will be eligible for enrollment. Exclusion criteria will include pregnancy, neutropenia (absolute neutrophil count <1000/μl), contraindication for retention enema, or food allergy not controlled for in the donor diet. Eligible patients will undergo written informed consent followed by randomization into intervention and control groups.