IDENTIFICATION OF MIXED GENOTYPES IN HELICOBACTER-PYLORI FROM GASTRICBIOPSY-TISSUE BY ANALYSIS OF UREASE GENE POLYMORPHISMS

PCR-RFLP analysis of the urease A and B genes was used to investigate the frequency that Helicobacter pylori from gastric biopsy specimens c omprised genotypically distinct strains. Seventy-five strains of H. py lori from 44 subjects from four geographically diverse locations were examined and 31 distinct urease gene profiles were identified. For mos t cultures, the totals of the RFLP sizes were within 4% of the 2.41-kb PCR product. Five strains were genomically more complex suggesting th ey contained a mixture of related genotypes. The validity of the test was confirmed by analysis of a known strain mixture and of single colo ny picks from biopsy cultures. Urease gene PCR-RFLP profiling was show n to be more sensitive than ribotyping for determining the genotypic h omogeneity of H. pylori.