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

Jessica R. Allegretti, Zain Kassam, Walter W. Chan

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. 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. 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). 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.