vacA s1m1 genotype and cagA EPIYA-ABC pattern are predominant among Helicobacter pylori strains isolated from Mexican patients with chronic gastritis

Purpose. Virulent genotypes of Helicobacter pylori vacA s1m1/cagA + /babA2 + have been associated with severe gastric diseases. VacA, CagA and BabA are polymorphic proteins, and their association with the disease is allele-dependent. The aims of this work were: (i) to determine the prevalence of H. pylori by type of chronic gastritis; (ii) to describe the frequency of cagA , babA2 and vacA genotypes in strains from patients with different types of chronic gastritis; (iii) to characterize the variable region of cagA alleles. Methodology. A total of 164 patients with chronic gastritis were studied. Altogether, 50 H. pylori strains were isolated, and the status of cagA , babA2 and vacA genotypes was examined by PCR. cagA EPIYA segment identification was performed using PCR and sequencing of cagA fragments of six randomly selected strains. Results/Key findings. The overall prevalence of H. pylori was 30.5 %. Eighty percent of the isolated strains were vacA s1m1 , and the cagA and babA2 genes were detected in 74 and 32 % of the strains, respectively. The most frequent genotypes were vacA s1m1/cagA + /babA2 - and v acA s1m1/cagA + /babA2 + , with 40 % (20/50) and 28 % (14/50), respectively. In cagA + , the most frequent EPIYA motif was -ABC (78.4 %), and EPIYA-ABCC and -ABCCC motifs were found in 10.8 % of the strains. A modified EPIYT-B motif was found in 66.6 % of the sequenced strains. Conclusion. H. pylori strains carrying vacA s1m1 , cagA + and babA2 - genotypes were the most prevalent in patients with chronic gastritis from the south of Mexico. In the cagA + strains, the EPIYA-ABC motif was the most common.