Introduction
Alterations of the small intestinal microbiome are linked to gastrointestinal symptoms and recent data suggest that there is an inverse relationship between the relative abundance of mucosa associated Veillonella spp and gastric emptying1. Previous studies have questioned the effect of gastrointestinal motility on the quality of bowel preparation for colonoscopy.
Aims & Methods
This study explored the possibility that the duodenal mucosa-associated microbiota (d-MAM) affects patient response to a standardized bowel preparation. We included data from 85 consecutive individuals (52 female, age 17 ~ 79 years (mean = 52.3) undergoing upper GI endoscopy with same day colonoscopy. The procedures were performed for the assessment of GI symptoms and/or a positive immunologic fecal occult blood test. All patients were recruited after informed consent and with approval from the local ethics committee. Bowel preparation was individualized based upon a previously developed protocol2 (and endoscopists rated the quality of the bowel preparation utilizing the Aronchick scale. Duodenal (D2) biopsies were obtained from each participant with an aseptic technique during endoscopy, snap frozen and stored at -80°C. Following gDNA extraction, amplicon libraries spanning the V6-V8 region of the 16S rRNA gene were constructed and sequenced using the Illumina MiSeq platform. Concurrent sequencing of reagent only controls was undertaken to exclude any non-duodenal sequences. Bioinformatics analysis was undertaken through the QIIME pipeline.
Results
The bowel preparation was rated in 65 patients as good or very good, 13 as Fair, and 7 as Poor. The within sample (alpha) diversities of duodenal MAM were not significantly different for subjects with different quality ratings of the bowel preparation. Interestingly though, those patients with a Poor-quality rating of their bowel preparation were found to possess a reduced relative abundance of Veillonella (and Prevotella) while the relative abundance of Pseudomonas was increased.
Conclusion
Given that a reduced relative abundance of the genus Veillonella is correlated with an increase in gastric emptying lag times, and that Pseudomonas is well recognized for its capacity to produce biofilms, the variable (and inverse) presence of these bacterial taxa (and Prevotella) raises the intriguing possibility that provide further evidence that the duodenal MAM influences gastrointestinal motor function.
References
1. Shanahan ER, Kang S, Staudacher H, et al. Alterations to the duodenal microbiota are linked to gastric emptying and symptoms in functional dyspepsia. Gut 2023;72:929-938.
2. Kutyla MJ, O'Connor S, Hourigan LF, et al. An Evidence-based Approach Towards Targeted Patient Education to Improve Bowel Preparation for Colonoscopy. J Clin Gastroenterol 2020;54:707-713.