Whole genome sequencing reveals novel genetic mutations of Helicobacter pylori associating with resistance to clarithromycin and levofloxacin

Comparative genomic analysis of Helicobacter pylori isolates from gastric cancer and gastritis in China

BACKGROUND

This study aimed to explore and compare the genomic characteristics and pathogenicity of Helicobacter pylori (H. pylori) strains derived from the gastric cancer (GC) and gastritis in the Chinese population.

METHODS

We performed whole genome sequencing on 12 H. pylori strains obtained from GC and gastritis patients in China. Additionally, we retrieved sequencing data for 20 H. pylori strains from various regions worldwide from public databases to serve as reference genomes. An evolutionary tree was constructed based on comparative genomics, and we analyzed the differences in virulence factors (VFs) and gene functions.

RESULTS

In the GC strains, we identified 1,544 to 1,640 coding genes, with a total length ranging from 1,549,790 to 1,605,249 bp. In the gastritis strains, we found 1,552 to 1,668 coding genes, with a total length spanning from 1,552,426 to 1,665,981 bp. The average length of coding genes was approximately 1,594 (90.91%) for GC strains and 1,589 (90.81%) for gastritis strains. We observed a high degree of consistency in the VFs predicted for both cohorts; however, there was a significant difference in their cagA status. Clustering analysis showed significant core single nucleotide polymorphisms (SNPs) differences between GC and gastritis strains, but no major differences in homologous proteins or gene islands. Subsequent pan-genomic and Average Nucleotide Identity (ANI) analyses indicated high homology among GC, gastritis, and other reference H. pylori strains. Furthermore, gene function annotation results showed substantial similarity in gene functions between the H. pylori strains from GC and gastritis patients, with specific functions primarily concentrated in metabolic processes, transcription, and DNA repair.

CONCLUSIONS

H. pylori strains derived from GC and gastritis patients exhibit differences in virulence factors and SNPs, yet they demonstrate high genomic homology across other levels in the Chinese population.

Helicobacter pylori resistance in Hainan Province, China: investigating phenotypes and genotypes through whole-genome sequencing

Helicobacter pylori is increasingly resistant to antibiotics, significantly lowering eradication rates and posing a major public health challenge. This study investigated the distribution of antibiotic-resistant phenotypes and genotypes of H. pylori in Hainan Province. It determined the minimum inhibitory concentrations (MICs) of six antibiotics using the E-test method and detected resistance genes via Sanger sequencing. Furthermore, we compared resistance detection based on phenotypic analysis and whole genome sequencing (WGS) across 19 clinical isolates of H. pylori. A total of 140 H. pylori strains were isolated. The resistance rates to levofloxacin (LEV), clarithromycin (CLA), and metronidazole (MTZ) were 37.9%, 40.0%, and 93.6%, respectively. Notably, only 3.3% of the strains were susceptible to all six antibiotics. Multidrug-resistant strains accounted for 25.0% of the total, with no resistance detected to amoxicillin (AMX), tetracycline (TET), or furazolidone (FR) during the study period. Genotypic resistance to CLA and LEV showed near-perfect concordance with phenotypic resistance, with Kappa values of 0.910 and 0.938, respectively. Although all isolates were phenotypically sensitive to TET, 16 exhibited a mutation in the 16S rRNA gene (A926G). All strains harboring the R16H/C mutation and truncated rdxA were resistant to metronidazole, demonstrating a specificity of 100%. Therefore, FR, AMX, and TET are recommended as suitable empirical treatment options for H. pylori infections in this region. Genotypic analysis provides a reliable method for predicting resistance to CLA and LEV. WGS proves to be a valuable tool for identifying novel resistance loci in H. pylori and contributes to the phylogenetic classification of strains.

Antibiotic Resistance of Helicobacter pylori: Mechanisms and Clinical Implications

Helicobacter pylori is a pathogenic bacterium associated with various gastrointestinal diseases, including chronic gastritis, peptic ulcers, mucosa-associated lymphoid tissue lymphoma, and gastric cancer. The increasing rates of H. pylori antibiotic resistance and the emergence of multidrug-resistant strains pose significant challenges to its treatment. This comprehensive review explores the mechanisms underlying the resistance of H. pylori to commonly used antibiotics and the clinical implications of antibiotic resistance. Additionally, potential strategies for overcoming antibiotic resistance are discussed. These approaches aim to improve the treatment outcomes of H. pylori infections while minimizing the development of antibiotic resistance. The continuous evolution of treatment perspectives and ongoing research in this field are crucial for effectively combating this challenging infection.

Antibiotic Resistance, Susceptibility Testing and Stewardship in Helicobacter pylori Infection

Despite the declining trend of Helicobacter pylori (H. pylori) prevalence around the globe, ongoing efforts are still needed to optimize current and future regimens in view of the increasing antibiotic resistance. The resistance of H. pylori to different antibiotics is caused by different molecular mechanisms, and advancements in sequencing technology have come a far way in broadening our understanding and in facilitating the testing of antibiotic susceptibility to H. pylori. In this literature review, we give an overview of the molecular mechanisms behind resistance, as well as discuss and compare different antibiotic susceptibility tests based on the latest research. We also discuss the principles of antibiotic stewardship and compare the performance of empirical therapies based on up-to-date resistance patterns and susceptibility-guided therapies in providing effective H. pylori treatment. Studies and clinical guidelines should ensure that the treatment being tested or recommended can reliably achieve a pre-agreed acceptable level of eradication rate and take into account the variations in antibiotic resistance across populations. Local, regional and international organizations must work together to establish routine antibiotic susceptibility surveillance programs and enforce antibiotic stewardship in the treatment of H. pylori, so that it can be managed in a sustainable and efficient manner.