MOLECULAR TYPING OF HELICOBACTER-PYLORI ISOLATES FROM ASYMPTOMATIC, ULCER AND GASTRITIS PATIENTS BY UREASE GENE POLYMORPHISM

The gastric-adapted bacterium Helicobacter pylori plays an important r ole in gastritis and ulcer disease, but no phenotypic typing scheme pr esently exists for this organism. With a view to the development of ge notypic typing, we have compared isolates of H. pylori from gastritis or ulcer patients with those from subjects exhibiting no disease. Vari ation was analysed at the urease genes, urea and ureCD, by employing P CR-generated probes in genomic Southern blot hybridizations. Whilst ur eA restriction fragments provided a fourfold subgrouping of strains, u reCD fragments were considerably more discriminatory. Twenty-four comb ined ureACD profiles were generated with Hind III, subdividing the 64 strains into 11 types and 13 single profiles. The most prevalent profi le (UI) was found in 33% of strains, almost all from gastritis or ulce r patients. On the other hand strains isolated from asymptomatic indiv iduals had the most diverse ureACD profiles. A key finding from this s et of isolates was that strains of H. pylori associated with general g astroduodenal disease were genetically more homogeneous than strains c arried by people without disease symptoms.