Randomised clinical trial: Faecal microbiota transplantation for irritable bowel syndrome with diarrhoea

Summary Background Faecal microbiota transplantation (FMT) has been shown to improve symptoms in a proportion of patients with irritable bowel syndrome (IBS). Aim We performed a randomised trial to assess the efficacy of FMT in patients with IBS. Methods We randomised 56 patients with diarrhoea‐predominant IBS 1:1 to FMT or placebo via the duodenal route at baseline and week 4. The primary outcome was > 50 points decrease in IBS severity scoring system (IBS‐SSS) score at week 12. Secondary outcomes were improvement in bloating and change in gut microbiota at week 12. After 12‐week follow‐up, those in the placebo group were assigned to receive open‐label FMT. Results At week 12, 57.1% in the FMT group and 46.4% in the placebo group achieved the primary endpoint ( p = 0.42). More patients receiving FMT than placebo had improvement in bloating (72% vs 30%; p = 0.005). In an open‐label extension, 65.2% and 82.4% of patients achieved, respectively, the primary endpoint and improvement in bloating. Faecal microbiome of patients in the FMT group showed a reduction in bacteria like Ruminococcus gnavus and enrichment of bacteria such as Lawsonibacter at week 12, while no change in the placebo group. Functional analyses showed that the hydrogen sulphide‐producing pathway decreased in patients who had FMT ( p < 0.05) accompanied by a reduction in contributing bacteria. There were no serious adverse events related to FMT. Conclusion FMT performed twice at an interval of four weeks did not significantly reduce IBS‐SSS score. However, more patients had improvement in abdominal bloating, which was associated with a reduction in hydrogen sulphide‐producing bacteria. ( ClinicalTrials.gov NCT03125564).