Virulent Helicobacter pylori genotypes are linked to greater gastric microbial diversity within subgroups and to distinct bacterial communities, suggesting that specific pathogenic factors influence which species co-colonize the stomach. Although overall α-diversity differences were non-significant, virulent genotypes were associated with higher diversity compared with less virulent counterparts, according to research presented at the American College of Gastroenterology 2025 Annual Scientific Meeting by presenting author Muhammad Miftahussurur, MD.
The study examined 66 H. pylori–positive gastric biopsies from Indonesia, a population with high gastritis rates but low gastric cancer incidence. Investigators determined H. pylori pathogenic factors (including CagA type, sabA, homA/B, iceA, and babB) from DNA extracted from bacterial cultures, and profiled the gastric microbiome by sequencing the 16S rRNA V3–V4 region using next-generation sequencing.
Helicobacter dominated infected stomachs, limiting other taxa. While α-diversity showed no significant differences overall, virulent H. pylori genotypes demonstrated greater microbial diversity, consistent with co-colonization by additional taxa. Several genera varied by pathogenic subtype, notably Veillonella species in samples with East Asian–type CagA and Klebsiella in samples lacking babB, noted Dr. Miftahussurur, of the Universitas Airlangga in Indonedia, and fellow researchers.
β-diversity analyses indicated that community composition differed by CagA polymorphisms, sabA status, homA/B, and iceA subtypes. As gastric atrophy worsened, H. pylori dominance remained stable while overall microbial diversity declined.
Microbial correlation analysis showed Helicobacter had a positive linear relationship only with Veillonella, whereas Streptococcus species correlated with multiple other gastric taxa. Predicted functional inference suggested several metabolic pathways became depleted as atrophy progressed.
H. pylori pathogenic factors shape gastric microbial diversity and community structure, and that non-Helicobacter residents may influence disease trajectories, the researchers concluded. Further work is needed to clarify whether these cohabiting taxa contribute to—or protect against—gastric pathology.
The study received the ACG Outstanding Research Award (Infections & Microbiome Category) and the ACG Presidential Poster Award.
The authors declared having no competing interests.