Long-term effects of fecal microbiota transplantation (FMT) in patients with irritable bowel syndrome

Background We recently found fecal microbiota transplantation (FMT) in irritable bowel syndrome (IBS) patients to be an effective and safe treatment after 3 months. The present follow-up study investigated the efficacy and safety of FMT at 1 year after treatment. Methods This study included 77 of the 91 IBS patients who had responded to FMT in our previous study. Patients provided a fecal sample and completed five questionnaires to assess their symptoms and quality of life at 1 year after FMT. The dysbiosis index (DI) and fecal bacterial profile were analyzed using a 16S rRNA gene-based DNA probe hybridization. The levels of fecal short-chain fatty acids (SCFAs) were determined by gas chromatography. Results There was a persistent response to FMT at 1 year after treatment in 32 (86.5%) and 35 (87.5%) patients who received 30-g and 60-g FMT, respectively. In the 30-g FMT group, 12 (32.4%) and 8 (21.6%) patients showed complete remission at 1 year and 3 months, respectively; the corresponding numbers in the 60-g FMT group were 18 (45%) and 11 (27.5%), respectively. Abdominal symptoms and the quality of life were improved at 1 year compared with after 3 months. These findings were accompanied by comprehensive changes in the fecal bacterial profile and SCFAs. Conclusions Most of the IBS patients maintained a response at 1 year after FMT. Moreover, the improvements in symptoms and quality of life increased over time. Changes in DI, fecal bacterial profile and SCFAs were more comprehensive at 1 year than after 3 months. (NCT03822299).