Oral and fecal microbiota in patients with diarrheal irritable bowel syndrome

Background: This study aimed at investigating the characteristics and correlation between oral (tongue coating) and fecal microbiota in patients with diarrheal irritable bowel syndrome (IBS-D).Methods: Fifty-two IBS-D patients were chosen, with ten healthy volunteers serving as the normal control group. Tongue coating samples and fecal samples of subjects were sequenced for the 16S rRNA gene (V4-V5). Bioinformatics analysis was done on the test data to investigate oral and fecal microbiota composition characteristics in IBS-D patients.Results: The microbial richness of tongue coating in IBS-D group was lower than that in the normal control group (P < 0.05). The beta diversity of tongue coating microbiota and fecal microbiota was significantly different in the IBS-D group compared to the normal control group (P < 0.05). Pseudomonadales (Pseudomonadaceae and Pseudomonas), Moraxellaceae, Parvimonas, Peptos-treptococcus, and Alloprevotella were considerably high in number the tongue coating samples of the IBS-D group in comparison to the normal control group. Similarly, the fecal samples from the IBS-D group were significantly enriched in Alphaproteobacteria, Pseudomonadales (Pseudomona-daceae and Pseudomonas), Acidaminococcaceae, Phascolarctobacterium, Alloprevotella, and Escher-ichia compared to the normal control group.Conclusions: The oral and fecal microbiotas of IBS-D patients differ from those of the control group; hence studying IBS-D from the perspective of the oral-gut microbiome axis is an interesting research avenue.