Small Intestinal Bacterial Overgrowth: Should Screening Be Included in the Pre-fecal Microbiota Transplantation Evaluation?

BACKGROUND: Fecal microbiota transplantation (FMT) is safe and effective for recurrent Clostridium difficile infection (rCDI) and often involves terminal ileal (TI) stool infusion. Patients report gastrointestinal (GI) symptoms post-FMT despite rCDI resolution. Small intestinal bacterial overgrowth (SIBO) screening is not routinely performed pre-FMT. The effect of donor/recipient SIBO status on FMT outcomes and post-FMT GI symptoms is unclear. We aim to evaluate the value of pre-FMT SIBO screening on post-FMT outcomes and symptoms.

METHODS: This was a prospective pilot study of consecutive adults with rCDI undergoing FMT by colonoscopy at a tertiary center. Routine pre-FMT screening and baseline lactulose breath tests (LBTs) were performed for donors and recipients. Positive LBT required a rise > 20 ppm in breath hydrogen or any methane level > 10 ppm within 90 min. The presence of GI symptoms and CDI resolution were assessed 8 weeks post-FMT. Fisher's exact/Student's t tests were performed for statistical analyses.

RESULTS: Twenty recipients (58.3 years, 85% women) enrolled in the study. Fourteen (70%) FMTs involved TI stool infusion. Four (20%) recipients and six (30%) donors had positive LBT pre-FMT. At 8 weeks post-FMT, 17 (85%) recipients had CDI resolution and five (25%) reported GI symptoms. Pre-FMT LBT result was not associated with post-FMT CDI resolution or GI symptoms. There was a trend toward increased GI symptoms among recipients receiving stool from LBT-positive donors (50 vs 14.2%, p = 0.09).

CONCLUSIONS: FMT is effective and well tolerated for rCDI. Positive LBT in asymptomatic donors may have an effect on post-FMT GI symptoms. Larger studies are needed.