Relief of irritable bowel syndrome by fecal microbiota transplantation is associated with changes in diversity and composition of the gut microbiota

OBJECTIVE: To evaluate the efficacy and safety of fecal microbiota transplantation (FMT) for refractory irritable bowel syndrome (IBS). METHODS: Microbiota suspensions from feces of the donors were injected into the intestines of 30 Chinese patients with refractory IBS. Microbiota composition analysis and genomic DNA extraction of fecal samples obtained from these patients at baseline and 1 month after FMT were performed. Clinical efficacy and safety of FMT were assessed using questionnaires covering four aspects of IBS therapeutic efficacy and assessment of adverse effects during a 6-month follow-up. RESULTS: FMT improved IBS gastrointestinal symptoms and alleviated depression and anxiety, as shown by the improved IBS-QOL, IBS-SSS, GSRS, HAMA and HAMD scores at 1 month and 3 months after FMT. A total adverse event rate of FMT was 6.7% (2/30). Gut microbiota analysis revealed that FMT responders had a significantly higher Shannon diversity index before FMT than non-responders. In addition, analysis of differences in bacterial composition before and after FMT in responders showed specific abundance of the phyla Verrucomincrobia and Euryarchaeota at 1 month after FMT. At the genus level, Methanobrevibacter and Akkermansia were the most abundant fecal microbiota 1 month after FMT compared with those before FMT. CONCLUSIONS: FMT may be an effective and safe therapeutic strategy for treating IBS that achieves a sustained clinical response 3-6 months after the first procedure. Changes in the diversity and dominant flora may contribute to its therapeutic effect.