Analysis of the structure of the Gastric Mucosal Microbial Community in Chronic Atrophic gastritis and Chronic Non-Atrophic Gastritis based on Helicobactor Pylori Negative

The aim of this study was to characterize the microbial composition of the gastric mucosa in Helicobacter pylori-negative patients with chronic atrophic gastritis (CAG) and chronic non-atrophic gastritis (CNAG).The samples of gastric mucosa tissue were obtained from 37 patients diagnosed with CNAG and CAG. Based on the status of H. pylori infection and histology, the patients were divided into two groups: CNAG (n=14) and CAG (n=23). The composition of the gastric microbiome was analyzed using 16S rRNA gene sequencing.At the phylum level, the two groups had the same most abundant bacterial phyla (Proteobacteria, Firmicutes, Actinobacteriota, Bacteroidota), although there was different richness among the two groups. At the genus level, the most abundant bacterial genera in the CAG group including Sphingomonas, Ralstonia, Brevundimonas, Methyloversatilis, and Pseudomonas, which in the CNAG group including Brevundimonas, Ralstonia, Sphingomonas, Methyloversatilis, and Acinetobacter. However, the most different bacterial genera in the CAG group were Sphingomonas, Ralstonia, Bradyrhizobium, and Pelomonas, while in the CNAG group, they were Brevundimonas, Rhodococcus, Hydrogenophaga, Bacteroides. The Sphingomonas exhibited a positive correlation with the Acidithiobacillus in the CAG group, while in the CNAG group, it exhibited a negative correlation with Brevundimonas,Hydrogenophaga, and Leifsonia. the alterations in the metabolism and signal transduction of gastric microorganisms in chronic atrophic gastritis, primarily manifested by a relative enrichment in cofactor and vitamin metabolism and the expression of xenobiotics biodegradation. However, there was a relative decrease in amino acid and nucleotide metabolism as well as intracellular protein synthesis and degradation.