Analysis of ileostomy stool samples reveals dysbiosis in patients with high-output stomas.

Construction of a diverting stoma can significantly reduce the onset of severe anastomotic leakage in patients with rectal cancer. High-output stoma is one of the most important potential surgical complications after anal function-preserving surgery with ileostomy. Culture-independent techniques have revealed the interaction of the complex intestinal bacterial ecology with various diseases. Our objective was to evaluate the differences in patient characteristics and gut microbiota distribution features in patients with high-output stomas. The cases of 24 consecutive patients who underwent curative resection for rectal cancer at our hospital between November 2016 and June 2018 were reviewed, and the patients were categorized into high-output and low-output groups. Their microbiota were analyzed using next-generation sequencing of ileostomy stool samples collected on postoperative day 7. There was a significant difference in the percentage of Bacteroidetes between the high-output and low-output groups (14.8% vs 0.5%; p=0.01). The percentage of Clostridium butyricum was increased in the low-output group (p=0.01). After the exclusion of those treated with the probiotic Miya-BM, whose principal component is C. butyricum, analyses revealed no significant differences between the high-output and low-output groups. This pilot study provides the first evidence correlating gut microbiota with the pathogenesis of high- output stoma compared with low-output stoma.