Involvement of shared mucosal‐associated microbiota in the duodenum and rectum in diarrhea‐predominant irritable bowel syndrome

BACKGROUND AND AIM: Most studies of diarrhea-predominant irritable bowel syndrome (IBS-D) focused on microbiota dysbiosis in a single segment of the intestine such as the colon. However, the intestine as a whole is involved in IBS-D and knowledge about the role of microbiota shared by the duodenum and rectum in IBS-D is limited. Here, we investigated the characteristics of mucosal microbiota shared by the duodenum and rectum in IBS-D patients. METHODS: We collected duodenal and rectal mucosal samples from 33 adult IBS-D patients and 15 healthy control (HC) subjects. The 454 pyrosequencing method and multiple bioinformatics analyses were used to examine bacterial 16S rRNA. Clinical data including symptoms and Bristol Stool Form were analyzed. RESULTS: Mucosal microbiota in duodenal samples differed from rectal samples in HC, while less difference was shown in IBS-D. More numbers in terms of shared operational taxonomic units and genera found in IBS-D compared with HC. The frequency of genera in the duodenum and rectum of HC differed from that of IBS-D. We identified 24 genera shared in the duodenum and rectum, which both changed dramatically in IBS-D. Among these 24 genera, half had similar trends in frequency differences, and the other half had opposite trends. The frequency of Faecalibacterium and Hyphomicrobium were associated with clinical data of IBS-D patients. CONCLUSIONS: Shared mucosal-associated microbiota in the duodenum and rectum appear to contribute to the etiology and pathophysiology of whole intestine of IBS-D and to be potential therapeutic targets.