Genetic polymorphisms of <i>helicobacter pylori</i> clinical isolates in St. Petersburg, Russia

Abstract

Introduction. Helicobacter pylori was proved to be the principal causative agent of gastroduodenal disorders in human. Although Russian Federation is among the countries with a high prevalence of H. pylori infection (6090%), currently there is a very limited number of studies evaluating H. pylori genotypes in Russia. Objective. Based on the assessment of virulence-associated cagA, oipA, and vacA genes, our study was aimed to determine H. pylori genotypes associated with the clinical outcomes in patients with H. pylori infection in St. Petersburg, Northwest Russia. Materials and methods. Using PCR for the detection of cagA, oipA, and vacA s, m, i allelic variants, we analyzed 61 H. pylori isolates isolated and cultured from biopsies collected during endoscopy of patients with chronic gastritis (G), duodenal ulcer (DU), and gastric cancer (GC). Results. The genetic diversity of H. pylori clinical isolates has been revealed (HGDI 0.88): 41 (67%) of 61 H. pylori isolates were cagA-positive, 38 (62%) oipA-positive. The proportions of cagA+ isolates differed in patients with G (56.7%) and DU (80.9%) (p = 0.06). The s, m, and i allelic variants of the vacA gene were detected in all strains, although the vacA s1 allele was significantly dominant in patients with DU (95.2%) rather than with G (64.9%) (p = 0.01). The vacA alleles m1 and i1 in the isolates from patients with G and DU were found in almost equal proportions: 45.9% and 42.8% for m1 allele, 45.9% and 47.6% for i1 allele, respectively. Seven isolates (11.5%) were positive for different mixed combinations of vacA alleles s, m, and i. Noteworthy, all vacA s2 strains were cagA-negative and had the m2 allele. OipA+ strains were found in almost equal proportions in patients with G (62.2%) and DU (57.1%) (p = 0.71). All three cagA- and oipA-positive isolates from patients with GC carried vacA s1/m1/i1 alleles. Different combinations of virulence-associated determinants constituted 17 genetic profiles. The most common combined genotype cagA+/oipA+/vacA s1/m1/i1 comprised 18 (29.5%) H. pylori isolates. Conclusion. We have determined predominant genotypes in the H. pylori population in the Northwest of Russia. The significant association between vacA s1 genotype of the pathogen and clinical manifestations of H. pylori infection has been established in our study.