Molecular Methods for Detecting Ulcerogenic Strains of H. pylori.

Certain nonconserved genotypic and phenotypic characteristics of H. pylori are associated with increased risk of peptic ulceration in the human host. These characteristics can be divided into two groups: first, those relating to vacuolating cytotoxin activity (1,2), and differences in the gene encoding the cytotoxin, vacA (3); second, those relating to the cytotoxin-associated gene, cagA (4,5).