Background. Thecagpathogenicity island (cag-PAI) is one of the most important virulent determinants ofHelicobacter pylori. An insertion sequence (IS) element ofcag-PAI (IS605) has been found to generateH. pyloristrains with varying virulence.Aim. To evaluate the impact of IS605 andcag-PAI onH. pyloristrains isolated from Taiwanese patients with severity of gastric diseases.Methods.H. pyloriisolates were cultured from gastric biopsies from 99 patients with peptic ulcer, chronic gastritis, and gastric carcinoma. Six distinct, well-separated colonies were isolated from each patient and analyzed by genotyping.Results.cagA,cagE,cagM,cagT,orf10, andorf13 were found to be present in 90.0%–100.0% of theH. pyloriisolates. A total deletion ofcagA,cagE,cagM,cagT,orf10, andorf13 was found in 1 isolate (1.0%). The IS605 element was found to be positive in 15.2% of the isolates. The presence of IS605 was higher inH. pyloriisolated from patients with gastric carcinoma (25.0%) than in patients with duodenal ulcer (6.5%) or chronic gastritis (6.3%) (P<0.001).Conclusions. The majority of the patients examined had intactcag-PAI. IS605 was present in 15.2% and was higher inH. pyloriisolated from patients with gastric carcinoma than in those with peptic ulcer.
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