Objective: Gastrointestinal microbiota may be involved in Helicobacter pylori- associated gastric cancer development. The aim of this study was to explore the possible microbial mechanisms in gastric carcinogenesis and potential dysbiosis arising from H. pylori infection. Design: Deep sequencing of the microbial 16S ribosomal RNA gene was used to investigate alterations in paired gastric biopsies and stool samples in 58 subjects with successful and 57 subjects with failed anti- H. pylori treatment, relative to 49 H. pylori negative subjects. Results: In H. pylori positive subjects, richness and Shannon indexes increased significantly (both p<0.001) after successful eradication and showed no difference to those of negative subjects (p=0.493 for richness and p=0.420 for Shannon index). Differential taxa analysis identified 18 significantly altered gastric genera after eradication. The combination of these genera into a Microbial Dysbiosis Index revealed that the dysbiotic microbiota in H. pylori positive mucosa was associated with advanced gastric lesions (chronic atrophic gastritis and intestinal metaplasia/dysplasia) and could be reversed by eradication. Strong coexcluding interactions between Helicobacter and Fusobacterium , Neisseria , Prevotella , Veillonella , Rothia were found only in advanced gastric lesion patients, and were absent in normal/superficial gastritis group. Changes in faecal microbiota included increased Bifidobacterium after successful H. pylori eradication and more upregulated drug-resistant functional orthologs after failed treatment. Conclusion: H. pylori infection contributes significantly to gastric microbial dysbiosis that may be involved in carcinogenesis. Successful H. pylori eradication potentially restores gastric microbiota to a similar status as found in uninfected individuals, and shows beneficial effects on gut microbiota.

Gastric cancer (GC) remains a significant public health burden in China, accounting for a high proportion of global incidence and mortality. Generally, the incidence and mortality of GC demonstrate marked demographic and geographic disparities in China, with higher rates in males, older adults and rural residents. Helicobacter pylori (H. pylori) infection serves as the main risk factor and contributes to approximately three-quarters of GC cases in China. Large-scale randomized controlled intervention trials in high-risk areas have provided robust evidence to support H. pylori eradication as an effective primary prevention strategy. Other established risk factors include high-salt diet and inadequate consumption of fresh fruits and vegetables. For secondary prevention, several national screening programs utilizing endoscopic examination have been conducted in high-risk populations, which were proven effective in early detection and mortality reduction. However, GC prevention and control in China still face great challenges, including increasing antibiotic resistance, limited screening coverage, and regional disparities in healthcare resources. Further efforts are urgently needed to integrate personalized risk prediction, family-based H. pylori control, and optimized cost-effective screening strategies for precision prevention to finally reduce the burden of GC.

In this study, a panel was established including differential metabolites, genera, and their interactions, which may help to discriminate high-risk subjects for progression from mild lesions to advanced precancerous lesions in short-term and long-term follow-up.

The increasing antibiotic resistance of Helicobacter pylori has had a serious impact on gastric cancer prevention. Our study aimed to profile the genomic characteristics and explore variants associated with resistance in H. pylori strains from a high-risk area of gastric cancer in China. We isolated 153 strains from a community-based cohort and assessed their susceptibility to six antibiotics by MIC Test Strip and genomic characteristics by whole-genome sequencing. Phylogenetic analysis identified the strains as an independent cluster within H. pylori East Asian population (hpEastAsia). HefA , an efflux pump gene, showed the highest differentiation in the Linqu strains compared with the other Chinese strains. Bacterial genome-wide association study (GWAS) identified 86 resistance variants covering 44 genes. Novel resistance variants were found in lon and babA for metronidazole, HP1168 for clarithromycin, hcpC for levofloxacin, and sabA for rifamycin. Two newly identified hefA mutations (R229K and A283V) showed significant associations with metronidazole ( P = 0.012) and tetracycline ( P = 0.044) resistance, respectively. HefA mutations and GWAS variants were integrated with the significant literature-reported mutations to optimize the prediction models for metronidazole, levofloxacin, clarithromycin, and tetracycline resistance with area under the receiver operating characteristic curves of 0.82–0.93. Double-antibiotic resistance models were established for clinical applicability. Furthermore, hefA expression may play a potential mediating role in the associations between mutations and resistance. This study identified genetic independence in the representative H. pylori strains from a high-risk area of gastric cancer. Optimized resistance prediction panels, including novel hefA mutations and GWAS variants, may provide preliminary guidance for localized precise treatment and helpful experiences for the similar high-risk populations. IMPORTANCE: Helicobacter pylori is a remarkable pathogen due to its virulence in gastric cancer and high genetic plasticity. Linqu County in China, a high-risk area of gastric cancer, faces serious antibiotic resistance issues and necessitates genomic profiling of local H. pylori strains. Phylogenetic analysis revealed the Linqu strains as a relatively independent cluster within the hpEastAsia population. Novel antibiotic resistance-associated hefA mutations and variants from our bacterial genome-wide association study in the Linqu strains were optimized to improve the prediction performances for single antibiotic and double-drug combination resistance compared with traditional literature-reported mutations. This study identified relative genetic independence and high differentiation in the representative H. pylori strains from a population with high risk of gastric cancer and high prevalence of antibiotic resistance. The optimized panels with novel variants improve antibiotic resistance prediction models compared with literature-reported mutations, providing guidance for localized precise treatment and suggesting prevention strategies for similar high-risk populations.