Structure and Metabolic Activity of the Gut Microbiota in Diarrhea-Predominant Irritable Bowel Syndrome Combined with Functional Dyspepsia

Gut dysbiosis presents in many digestive diseases. The aim of this study is to investigate the composition of the gut microbiota and its metabolic activity in patients with diarrhea-predominant irritable bowel syndrome combined with functional dyspepsia (I + D). This study included 60 patients with I + D and 20 healthy controls. Gut microbiota composition was studied using 16S rRNA gene sequencing. The short-chain fatty acids (SCFAs) spectrum was determined via gas-liquid chromatography. Patients with I + D had an increase in the abundance of Holdemanella, Erysipelotrichaceae, Erysipelotrichales, Prevotellaceae, Agathobacter, Slackia, Lactococcus, Pseudomonadaceae, Stenotrophomonas, Xanthomonadaceae, Rhizobiaceae, Erysipelatoclostridiaceae, Lachnospiraceae, and other taxa in addition to a decrease in the abundance of Frisingicoccus, Ralstonia, Burkholderiaceae, Hungatella, Eisenbergiella, Parabacteroides, Peptostreptococcaceae, Merdibacter, Bilophila, Rikenellaceae, Tannerellaceae, Bacteroidaceae, and Flavonifractor in comparison to controls. Patients with I + D showed significantly higher total SCFA content in feces; increased absolute content of acetic acid, propionic acid, butyric acid, and isoacids; and a significant negative shift in the anaerobic index. The relative levels of the main SCFAs and isoacids in the patient group did not differ significantly from those in the control group. The fecal acetate and isoacid levels correlated with the severity of diarrhea. The fecal butyrate level correlated with the severity of flatulence.

Automated summary

This study investigated the composition and metabolic activity of the gut microbiota in patients with diarrhea-predominant irritable bowel syndrome combined with functional dyspepsia (I + D). The study found significant differences in the abundance of certain gut bacteria as well as higher levels of short-chain fatty acids (SCFAs) in the feces of patients compared to healthy controls. Additionally, the levels of certain fatty acids in the feces correlated with the severity of the symptoms.