HETEROGENEOUS HELICOBACTER-PYLORI ISOLATES FROM MEMBERS OF A FAMILY WITH A HISTORY OF PEPTIC-ULCER DISEASE

Background & Aims: Duodenal ulcer formation in persons infected with H elicobacter pylori correlates with the expression of the cytotoxin-ass ociated gene A (cagA) and the vacuolating cytotoxin (VacA). The aim of this study was to assess the occurrence of cagA and VacA variants amo ng H. pylori isolates, Methods: H. pylori was isolated from 8 members of one family with a history of peptic ulcer disease (PUD), Each strai n was characterized by random amplified polymorphic DNA (RAPD) fingerp rinting. cagA was detected by polymerase chain reaction (PCR), Souther n blotting, and colony hybridization, Viable H. pylori was added to ma mmalian cells to assess their cytotoxin activity, Results: The RAPD pa tterns of the 8 patients' strains were similar. analysis of 10 single colonies from the primary culture plates showed that all but 1 subject harbored multiple H. pylori subtypes. The proportion of cagA-positive colonies on the primary culture plates ranged from 0% to 90% between the isolates from all patients, in addition, the different H. pylori s ubtypes showed no cytotoxin activity in mammalian cells, Conclusions: Genotypic comparison of H, pylori isolated from different patients req uires analysis of multiple colonies selected from the primary culture plate, In addition, infection by cagA-positive H. pylori in the family Members with PUD (subjects 2-8) is consistent with the observed assoc iation between cagA positivity and PUD.