Epidemiology of cagA/vacA genes in H. pylori isolated from children and adults in Poland.

Serious lesions in gastric mucosa seem to be a result of infection with more pathogenic H. pylori strains. It was shown that two different proteins: CagA and VacA are the pathogenicity markers of H. pylori. CagA/VacA profile is associated with high intensity of inflammation and development of peptic ulcer disease. Presence of CagA protein depends on possession by a strain of cagA gene. VacA protein is expressed in every strain, but particular alleles of vacA gene are responsible for different levels of cytotoxin production. We estimated frequency of the cagA gene and particular alleles of vacA gene in 84 H. pylori strains by PCR method. Eighty percent of children and 72.4% of adults were infected with cagA(+) H. pylori strains. Presence of cagA gene was correlated with active gastritis in 60% of infected children and adults. Majority of H. pylori strains represented s1m2 and s1m1 vacA alleles' combinations that are responsible for high and medium level of cytotoxin production. Our data may suggest high risk of development of serious consequences of H. pylori infection especially in children treated unsuccessfully.