The Gut Microbiome at the Onset of Inflammatory Bowel Disease

IBD

David H. Bruining, MD, FASGE reviewing Rimmer P, et al. Gastroenterology 2026 Mar.

Disruption of the gut microbiome has been linked to the development of inflammatory bowel disease (IBD) and considered a potential diagnostic and prognostic marker. However, there is a lack of robust evidence, which is further complicated by inconsistent findings. Researchers aimed to address these issues by performing a systematic review and novel secondary bioinformatic reanalysis of sequence data.

Among 36 eligible studies, 18 contributed to the integration of 16S rRNA sequence datasets. These included samples from 1743 patients (678 with Crohn’s disease, 399 with ulcerative colitis, 1 IBD-unclassified, 122 IBD “not-specified,” 130 healthy controls, 405 symptomatic controls, and 8 familial controls). Core microbial disruptions at IBD onset (treatment-naïve) included depletion of anaerobes and enrichment of oxygen-tolerant and oral bacteria (Pseudomonas, Haemophilus, Fusobacterium, and Granulicatella).

Comment:

This novel bioinformatic reanalysis has revealed disruptions in the gut microbiome at IBD onset. Future research will likely explore whether targeting these disruptions can alter disease progression.

Note to readers: At the time we reviewed this paper, its publisher noted that it was not in final form and that subsequent changes might be made.

David H. Bruining, MD, FASGE

Bio and Disclosures

Citation(s):

Rimmer P, Zhang F, Scott G, et al. The gut microbiome at the onset of inflammatory bowel disease: a systematic review and unified bioinformatic synthesis. Gastroenterology 2026;170:539-556. (https://doi.org/10.1053/j.gastro.2025.09.014)