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Phenotypic and Genotypic Antibiotic Resistance Patterns in Helicobacter pylori Strains From Ethnically Diverse
Margarita Camorlinga-Ponce1, Alejandro Gómez-Delgado1, Emmanuel Aguilar-Zamora1,2
1Unidad de Investigación en Enfermedades Infecciosas, UMAE Pediatría, Instituto Mexicano del Seguro Social, Ciudad de México, Mexico.
Abstract:
Helicobacter pylori strains carry a range of mutations in genes that confer antimicrobial resistance and restrict the available options to treat the infection. Latin America is a region that conserve a large number of indigenous communities relatively isolated that practice a traditional medicine without consumption of drugs. We hypothesized that rates of antibiotic resistance are lower in these communities. Recent progress in whole-genome sequencing has allowed the study of drug susceptibility by searching for the known mutations associated with antibiotic resistance. The aim of this work was to study trends of antibiotic resistance over a 20-year period in Mexican H. pylori strains and to compare susceptibility between strains from Mexican mestizos and from indigenous population; we also aimed to learn the prevalence of mutational patterns in genes gyrA, gyrB, rdxA, frxA, rpsU, omp11, dppA, and 23S rRNA and its association with phenotypic tests. Resistance to clarithromycin, metronidazole, amoxicillin and levofloxacin was determined in167 H. pylori isolates by E-test, and the occurrence of mutational patterns in specific genes was determined by whole genome sequencing (WGS). The trend of resistance over 20 years in mestizo isolates showed significant resistant increase for clarithromycin and levofloxacin to frequencies that banned its clinical use. Resistance in H. pylori isolates of native communities was lower for all antibiotics tested. Phenotypic resistance showed good to moderate correlation with genotypic tests. Genetic methods for characterizing antibiotic resistance require further validation in each population.
Insights
Antibiotic resistance in Helicobacter pylori is increasing in Mexican mestizo populations but remains lower in indigenous communities. Genetic and phenotypic testing showed good correlation for antimicrobial resistance patterns.
Area of Science:
- Microbiology
- Genetics
- Epidemiology
Background:
- Antimicrobial resistance in Helicobacter pylori (H. pylori) complicates treatment options globally.
- Latin America's indigenous communities, with limited drug exposure, offer a unique model to study H. pylori antibiotic resistance.
- Whole-genome sequencing (WGS) enables efficient identification of resistance-associated mutations.
Purpose of the Study:
- To investigate H. pylori antibiotic resistance trends over 20 years in Mexican populations.
- To compare H. pylori susceptibility between mestizo and indigenous communities in Mexico.
- To analyze the prevalence and association of specific gene mutations (gyrA, gyrB, rdxA, frxA, rpsU, omp11, dppA, 23S rRNA) with phenotypic resistance.
Main Methods:
- Phenotypic resistance to clarithromycin, metronidazole, amoxicillin, and levofloxacin was assessed in 167 H. pylori isolates using E-tests.
- Whole-genome sequencing (WGS) was employed to identify mutations in key antibiotic resistance genes.
- Correlation between genotypic and phenotypic resistance data was evaluated.
Main Results:
- A significant increase in resistance to clarithromycin and levofloxacin was observed in Mexican mestizo H. pylori isolates over the 20-year study period, reaching levels precluding clinical use.
- H. pylori isolates from indigenous communities exhibited lower resistance rates across all tested antibiotics compared to mestizo isolates.
- Phenotypic antimicrobial resistance demonstrated a good to moderate correlation with genotypic findings.
Conclusions:
- H. pylori antibiotic resistance patterns differ significantly between Mexican mestizo and indigenous populations.
- The rising resistance trends in mestizo populations highlight the urgent need for updated treatment guidelines.
- Genotypic methods for detecting H. pylori antibiotic resistance require further validation across diverse populations.
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