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, Peptostreptococcus, 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 (Pseudomonadaceae and Pseudomonas), Acidaminococcaceae, Phascolarctobacterium, Alloprevotella, and Escherichia 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.