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The study compared the effectiveness of two different primer sets for detecting and evaluating the prevalence of the babA2 gene in 52 H. pylori clinical isolates from patients with chronic gastritis (n=32), duodenal ulcer (n=16) and stomach cancer (n=4) in St. Petersburg, Russia. The PCR was used for detection of the babA2 gene with 271 bp and 832 bp primer sets followed by sequencing of the PCR-amplicons. The largest proportion of babA2-positive strains - 90.4% (47/52) was detected using a 271 bp PCR primer set. Detection of the 832 bp PCR positive samples was observed only in 51.9% of cases (27/52). The largest proportion of babA2-positive strains - 90.4% (47/52) was detected using 271 bp PCR primer set; detection of 832 bp PCR product was observed only in 51.9% cases (27/52), however, there were no significant differences in the babA2 gene detection rates (p>0.05). Bioinformatic analysis revealed a homology of Sanger sequenced PCR products 271 bp and 832 bp of babA2 gene with regions of the babA2, babA1, and chimeric babA/B genes of H. pylori strains annotated in the NCBI database. Regardless of the primer set used, the presence of babA2 was not significantly associated with duodenal ulcer nor gastric cancer (p>0.05). The combination of the three babA2, cagA, and vacAs1 genes did not reveal any association between the presence of babA2 gene and cagA/vacAs1 genes in H. pylori strains (p>0.05). Thus, none of the two primer sets (271 bp and 832 bp) appears sufficiently informative for detecting the babA2 gene to assess virulence of H. pylori Russian strains., Competing Interests: The authors declare no conflict of interest.

Aim: Study H. pylori strains circulating in St. Petersburg among patients with various gastrointestinal tract pathology as well as study of frequency of infection by H. pylori based on serological markers data among this group of patients., Materials and Methods: By using serological method 162 individuals with various chronic diseases of stomach and duodenum were examined. The presence in blood serum of IgG against H. pylori bacterial antigen and IgG against its toxin--CagA was studied. 129 patients were examined bacteriologically, biopsy samples of stomach mucous membrane were studied. PCR in real time format was used for study of H. pylori strains (49) and biopsy samples (36) of stomach mucous membrane., Results: The analysis performed showed that on the territory of St. Petersburg H. pylori strains containing cagA gene predominate (81.63% of the isolated strains). Genotyping of strains by vacA showed that s1m1 genotype was more frequent (in 57.14% of cases). The fraction of CagA positive strains in patients in St. Petersburg is maximum for stomach cancer (90.8%), whereas for peptic ulcer disease and gastritis it is 64.7% and 72.2%, respectively. In patients with stomach and duodenum pathology the parameters of seropositivity for H. pylori were significantly higher than in individuals without clinical manifestations of H. pylori infection (86.72% against 65.09%; p < 0.05)., Conclusion: The data obtained on increase of fraction of CagA positive strains among H. pylori circulating in St. Petersburg determine the importance of conducting eradication H. pylori.

Aim: Study of prevalence of Helicobacter pylori infection in one organized children community of St. Petersburg in the current period., Materials and Methods: 390 children and adolescents of one of the general education schools of St. Petersburg were examined. Presence in blood sera of IgG to bacterial antigen of H. pylori and IgG to its CagA toxin by ELISA method was studied. In 222 children feces samples were studied. Determination of presence of H. pylori antigen in the feces was carried out by using Helicobacter pylori antigen ELISA Kit, Immundiagnostik test system., Results: Comparison of H. pylori infection prevalence in children of various age revealed that infection is minimal in children aged 7 - 8 years (36.84%) and reaches maximum levels in students aged 14 years (66.67%). Screening result shows that there are 2 waves of H. pylori infection (the first peak was detected in 11 years, the second - in 14 years). Excess weight in H. pylori positive students is present less frequently (19.89% versus 30.13%). The difference is more notable in boys (20.25% and 38.75% respectively)., Conclusion: A sufficiently high level of infectivity by H. pylori in the students of this school was detected. It was established, that seropositivity increases with student age and reaches maximum levels in upperclassmen. 2 waves of H. pylori infection curve are noticed. It was detected that excess weight occurs more frequently in children not infected by helicobater (p<0.05). Combination of various diagnostic methods gives more precise information on the presence of H. pylori infection.

Aim: Studies of Helicobater pylori infection rate among population of North-western federal district including St. Petersburg in 2007 - 2009., Materials and Methods: 1021 individuals with various digestive tract pathologies as well as healthy individuals and blood donors were examined. 378 children and adolescents up to 19 years of age, and 643 adults 20 - 80 years of age were among the examined individuals. IgG to H. pylori complex antigen and IgG to its CagA toxin were determined in blood sera., Results: Infection rate among children and adolescents was 40.48%, CagA positive strain infection rate--34.92%. Among adults these parameters were 63.61% and 49.61%, respectively. During the 3 year study a tendency of CagA positive strain rate increase was noted among children and adolescents. Prevalence of H. pylori infection in subjectively healthy individuals, intestine oncology disease and gastric cancer patients was 55.1%, 67.16% and 83.33%, respectively., Conclusion: High rate of infection and CagA positive strain prevalence among children and adolescents can be considered as a possible factor of gastritis and ulcer rate increase in these age groups.

The data on the structure and biological activity of the lipopolysaccharide (LPS) of Yersinia as an important virulence factor are analyzed. The biological effects of LPS are characterized by dose dependence: small doses stimulate the intensity of phagocytosis, while large doses decrease phagocytic activity and produce cytotoxic effect. Yersinia LPS plays an important role in the development of such consequences of yersiniosis as reactive arthritis, erythema nodosum, Reiter's syndrome. Yersinia LPS is a widespread component for the diagnostics of yersiniosis and pseudotuberculosis.