Identification of mixed genotypes in Helicobacter pylori from gastric biopsy 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 comprised genotypically distinct strains. Seventy-five strains of H. pylori from 44 subjects from four geographically diverse locations were examined and 31 distinct urease gene profiles were identified. For most cultures, the totals of the RFLP sizes were within 4% of the 2.41-kb PCR product. Five strains were genomically more complex suggesting they contained a mixture of related genotypes. The validity of the test confirmed by analysis of a known strain mixture and of single colony picks from biopsy cultures. Urease gene PCR-RFLP profiling was shown to be more sensitive than ribotyping for determining the genotypic homogeneity of H. pylori.