A large international microbiome study has identified a distinct and consistent bacterial shift at the very onset of inflammatory bowel disease (IBD), strengthening the case for microbiome-based early diagnosis and prevention strategies.
Published in Gastroenterology, the study is the first to pool and harmonize raw microbiome data across multiple cohorts, analyzing more than 1,700 treatment-naïve children and adults from 11 countries at the time of initial IBD diagnosis.
The analysis shows that newly diagnosed patients with Crohn’s disease and ulcerative colitis experience a pronounced loss of beneficial anaerobic bacteria responsible for fermenting complex carbohydrates and maintaining gut homeostasis. At the same time, there is a striking increase in oxygen-tolerant bacteria—many originating from the oral cavity—that migrate and establish themselves in the gut. Species such as Granulicatella and Haemophilus, typically found in the mouth, were consistently detected in the intestinal microbiome of IBD patients.