Oral microbiome test as an alternative diagnostic tool for gastric alterations: A prospective, bicentric cross-sectional study.

The human microbiome plays a pivotal role in influencing various physiological processes and maintaining overall well-being, including the gastric system. Current diagnostic tests for gastric diseases often involve invasive procedures, sampling limitations, and medication effects, leading to potential diagnostic errors and discomfort to patients. Considering the connection between oral and gastric microbiomes, this cross-sectional study aimed to assess the diagnostic potential of the oral bacterial profile in patients undergoing upper digestive endoscopy. Oral samples from 266 participants across two Brazilian sites (Belterra and Sao Paulo) were sequenced and subjected to bioinformatic analysis to identify microbiome composition across endoscopy outcome groups, exploring alpha and beta-diversity, richness, and differential abundance and prevalence. Prevotella, Haemophilus, Fusobacterium, Neisseria, and Streptococcus were the most abundant genera observed. No significant associations were found between alpha diversity profiles and endoscopy outcomes; beta diversity analyses similarly showed no correlations. Overall, the study did not establish the oral microbiome as a reliable marker for gastric health, underscoring the necessity for broader studies in the development of non-invasive diagnostic tests.