P3009 - Small Intestinal Microbiome Assessed by Deep Enteroscopy

Tuesday, October 26, 2021

10:30 AM – 4:00 PM PT

Location: Shoreline Exhibit Hall

Has Audio

Presenting Author(s)

Jamie Bering, MD

Mayo Clinic
Scottsdale, AZ, United States

Jamie Bering, MD¹, Kathrine McAulay, PhD¹, Thomas Grys, PhD², Kevin C. Ruff, MD¹
¹Mayo Clinic, Scottsdale, AZ; ²Mayo Clinic, Phoenix, AZ

Introduction: Dysbiosis of the intestinal microbiome is associated with a wide variety of disorders. Yet, the gastrointestinal microbiota, and in particular, small bowel microbiota, remains difficult to characterize due to sampling challenges. Balloon-assisted enteroscopy allows for deep intestinal sampling compared to traditional endoscopic techniques. To better characterize the microbiome of the small bowel, we obtained mucosal brushing samples during deep enteroscoy for further analysis.

Methods: Mucosal brushings were obtained from 8 participants undergoing anterograde or retrograde enteroscopy. Samples were collected at one or more of the following distances: 5, 75, 150, 225, and 300 cm (Table 1) and deposited in 5 mL sterile saline. Specimens were stored at -80 C immediately after the procedure. Participants collected stool specimens at home prior to the procedure and again approximately one week after the procedure. Stool specimens were aliquoted upon receipt and stored at -80 C. One aliquot of each specimen was submitted to the ASU Genomics Core (11 stool, 22 mucosal brushings).

Results: Richness was assessed at each sampling site by calculating the number of observed Amplicon Sequence Variants (ASVs) (Figure 1A), the Chao1 Richness Estimator (Figure 1B) and the Abundance Based Coverage Estimator (Figure 1C). Significantly more ASVs were detected in stool specimens than mucosal brushing specimens, specifically between stool and jejunum specimens (p < 0.01, Wilcoxon, BH adjusted).

A total of 23 phyla were detected; however, the abundance of Firmicutes, Proteobacteria, Bacteriodota, and Actinobacteriota accounted for the majority of reads (Figure 2). Organisms belonging to the phylum Firmicutes were more abundant in ileal and stool specimens, while organisms belonging to the phylum Proteobacteria were more abundant in duodenal and jejunal specimens (Figure 3). Specifically, the difference between jejunal and stool specimens in both cases was significant (p < 0.005, Wilcoxan, BH adjusted).

Discussion: When evaluating the GI microbiome on a phylum level, stool composition is distinct from the proximal small bowel, but not from the ileum. Although there were a small number of participants included in this study, the results suggest that stool may not be a comparable proxy for the small intestinal microbiome. Furthermore, we feel these results are proof of concept of this strategy as a viable technique for small intestinal microbiome evaluation.

Figure: Figure 1: Richness assessed by Amplicon Sequence Variants (ASVs) (Figure 1A), Chao1 Richness Estimator (Figure 1B) and Abundance Based Coverage Estimator (Figure 1C).

Figure 2: All phyla detected by sampling site.

Figure 3: Most abundant phyla by sampling site.

Distance	Antegrade Enteroscopy Site	Retrograde Enteroscopy Site
5	Duodenum	Distal Ileum
75	Proximal Jejunum	Mid Ileum
150	Mid Jejunum	Proximal Ileum
225	Distal Jejunum	Distal Jejunum
300	Proximal Ileum	Proximal Jejunum

Table: Sampling sites for antegrade and retrograde deep enteroscopy.

Disclosures:

Jamie Bering indicated no relevant financial relationships.

Kathrine McAulay indicated no relevant financial relationships.

Thomas Grys indicated no relevant financial relationships.

Kevin Ruff indicated no relevant financial relationships.

Jamie Bering, MD¹, Kathrine McAulay, PhD¹, Thomas Grys, PhD², Kevin C. Ruff, MD¹. P3009 - Small Intestinal Microbiome Assessed by Deep Enteroscopy, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.