Genotypes of Helicobacter pylori in Lithuanian families

Infection by Helicobacter pylori is very common in Eastern Europe, but the genotypes of predominant strains and prevalence of single vs. multiple infection in this geographic region have not been much studied.

H. pylori was cultured from 13 Lithuanians belonging to six families, and characterized by arbitrarily primed PCR (RAPD) DNA fingerprinting, and by hybridization and PCR tests for polymorphic virulence-associated and neutral genetic markers.

Eleven distinct strains were identified: seven carried the cag pathogenicity island (PAI) and the s1 (generally toxigenic) allele of the vacuolating cytotoxin gene (vacA); the other four were cag- and carried the vacA s2 (nontoxigenic) allele; five of the seven vacA s1 strains carried an m1 middle region allele of vacA, whereas all other strains carried m2 alleles, which are generally less toxigenic; four strains carried the virulence-associated iceA1 gene, and the other seven carried the completely unrelated iceA2 gene at the same locus. Insertion sequences IS605 and IS606 and a plasmid replication gene (repA) were also found in some strains. RAPD fingerprinting identified a mixed infection in just one of the 13 persons. In two families, two of the members harbored the same strain, whereas in the other four families each member tested carried a different strain. Resistance to metronidazole (Mtz) was found in two persons; each of them also carried MtzS strains that were indistinguishable from the coresident MtzR strain by RAPD fingerprinting, and that were thus closely related in overall genotype.

The distribution of genotypes of Lithuanian H. pylori strains resembles that seen in Western Europe. This finding has important implications for understanding modes of H. pylori transmission and evolution.