The potential roles of gut microbiome in Anal fistula

Background: Anal fistula is a common proctological disease, but the thorough mechanisms of the anal fistula formation are still unclear. An increasing number of studies have revealed that the key role of gut microbiome in intestinal diseases. Methods: The microbiome samples were extracted by repeatedly wiping the rectal wall with intestinal swab. Before this operation, the whole intestine of all participants was irrigated and the score of the Boston bowel preparation scale reached 9. We used 16S rRNA gene sequencing to profile the intestinal microbiome and aimed to determine if the microbiome is different between anal fistula patients and healthy individuals. Results: The biodiversity of gut microbiome revealed significant difference between anal fistula patients and healthy individuals. 36 discriminative taxa were identified by LEfSe analysis between two groups. At the phylum level, Synergistetes was enriched in anal fistula patients, while Proteobacteria was higher in healthy individuals. We also found that at the genus level, Blautia, Faecalibacterium, Ruminococcus, Coprococcus, Bacteroides, Clostridium, Megamonas and Anaerotruncus were highly enriched in anal fistula patients, while the microbiome of healthy individuals was enriched with Peptoniphilus and Corynebacterium. The spearman correlations showed the extensive and close association among genera and species. Finally, a diagnostic prediction model was constructed by random forest classifier, and the AUC reached 0.990. Conclusion: This study gave an important hint for analyzing gut microbiome in anal fistula patient.