# Bacteroides, Metabolites, and Lymphocytes: A Triad of Biomarkers in Small Intestinal Bacterial Overgrowth

## TL;DR

This study explores how SIBO is linked to gut bacteria, metabolites, and lymphocyte levels, identifying potential biomarkers for diagnosis.

## Contribution

The study identifies lymphocyte count as a novel predictor of SIBO in non-obese middle-aged and elderly men.

## Key findings

- Lymphocyte count is a better predictor of SIBO in non-obese middle-aged and elderly men.
- SIBO is significantly associated with symptoms like diarrhea and acid reflux.
- Bacteroides dominates the gut microbiota in SIBO patients, with altered metabolic pathways.

## Abstract

The purpose of this study was to investigate the clinical characteristics of small intestinal bacterial overgrowth (SIBO) and analyze its relationship with changes in intestinal microbiota and metabolites. The study included patients from Beijing Shijitan Hospital (Feb 2021–Nov 2023) who underwent hydrogen‐methane breath tests, hematological tests, and completed questionnaires. Baseline characteristics of SIBO patients were analyzed using descriptive statistics and independent t‐tests. Logistic regression and Receiver Operating Characteristic (ROC) curve analysis identified potential SIBO predictors. Chi‐square tests assessed the association between SIBO and symptoms. Stool samples from 29 patients underwent 16S rRNA sequencing to analyze gut microbiota and metabolites. Then we explored links between microbiota, metabolites, symptoms, and serum markers. 405 persons in all completed the hydrogen methane breath test, of whom 109 (26.91%) were in the SIBO− and 296 (73.09%) were in the SIBO+. No significant differences were observed between the SIBO+ and SIBO− groups in terms of gender, age, or BMI. However, lymphocyte counts were significantly different between the groups, with lymphocyte count proving to be a better predictor of SIBO in middle‐aged and elderly non‐obese men. SIBO was significantly associated with diarrhea and acid reflux symptoms. 16S rRNA sequencing of stool samples from 29 patients revealed that Bacteroides was the predominant intestinal microbiota in SIBO patients. Metabolic pathways involving various metabolites were identified as significantly altered in these patients. Additionally, there were significant correlations between various intestinal flora and metabolites with serum markers.

We identified lymphocyte count as a potential predictor of SIBO in middle‐aged and elderly non‐obese men. Additionally, our findings revealed significant associations between SIBO and symptoms such as diarrhea and acid reflux, as well as alterations in gut microbiota—specifically the predominance of Bacteroides—and metabolic pathways.