CagA and cytotoxicity of Helicobacter pylori are not markers of peptic ulcer in Japanese patients

Background. The infection with cagA-positive Helicobacter pylori strains is reported to be associated with peptic ulcer disease in developed countries , but it is controversial in Asia. To investigate the relationship between the virulence factors of H. pylori and peptic ulcer disease in Japan, we co mpared these between ulcer and nonulcer patients. Materials and Methods. Seventy-four strains of clinically isolated H. pylor i obtained from 22 gastric ulcer (GU), 23 duodenal ulcer (DU), and 29 chron ic gastritis (CG) patients were studied. The presence of vacA and cagA gene was examined by polymerase chain reaction method using two different prime r sets. We evaluated the proliferation-inhibiting and lethal cytotoxicity o f culture supernatants using the alamarBlue assay. Results. The vacA gene was identified in all strains by the original primer s. S1 strains were found in 90.9% (20/22) from GU, 95.7% (22/23) from DU, a nd 96.6% (28/29) from CG patients. The prevalence of cagA gene determined b y the first, and second primers was 90.9% (20/22), 90.9% (20/22) in strains from GU, 87.0% (20/23), 91.3% (21/23) from DU, and 86.2% (25/29), 89.7% (2 6/29) from CG patients, respectively. The supernatant showed cytolethal eff ect in 95.5% (21/22) of strains from GU, in 100% (23/23) from DU, and in 93 .1% (27/29) from CG patients. There was no significant difference in the pr evalence of the virulence factors between H. pylori strains isolated from p atients with peptic ulcers and those with chronic gastritis. Conclusions. These results indicate that cagA gene status and the prolifera tion-inhibiting and lethal cytotoxicity of supernatant are not reliable mar kers of ulcerogenicity of H. pylori in Japanese patients.