Fecal and muscosal microbiota of patients with irritable bowel syndrome with diarrhea (IBS-D) and healthy controls are very similar and are not sufficient to explain the reported altered physiology and symptomology of IBS-D, a recent study suggests. The cohort included 23 diarrhea-predominant IBS patients and 24 healthy controls (HC). Fresh stool samples were collected from participants prior to the collection of colonic mucosal samples from and unprepped bowel. After DNA extraction, 16S rRNA genes were sequenced by 454 pyrosequencing and analyzed using the QIIME pipeline. Researchers found:

• The fecal microbiota of IBS-D patients was found to have reduced enteric richness compared to HC.
• However, no differences were observed between the 2 groups within the mucosal microbiota.
• Within the luminal niche, the relative proportions of Faecalibacterium genus were found to be lower in IBS-D vs HC and the Dorea genus was higher in IBS-D.
• None of the taxa proportions were significantly different in IBS-D patients vs HC.