Association of heterogenicity of Helicobacter pylori cag pathogenicity island with peptic ulcer diseases and gastric cancer.

OBJECTIVE: To investigate the frequency and integrity of certain cag pathogenicity island genes (cagPAI) in Helicobacter pylori strains and their association with peptic ulcer disease (PUD) and gastric cancer.

MATERIAL AND METHODS: We enrolled 240 adult patients [120 with functional dyspepsia (FD), 50 with PUD and 70 with gastric cancer] undergoing upper gastrointestinal endoscopy. H. pylori infection was diagnosed when either culture or any two of the three tests (rapid urease test, histopathology and specific ureA PCR) were positive. DNA extracted from H. pylori isolates and positive gastric tissues were tested by PCR for the presence of different genes of cagPAI using specific primers.

RESULTS: A total of 122 (51%) patients were H. pylori positive. Frequencies of cagPAI genes cagA, cagE, cagT and cagM in H. pylori strains from different groups of patients were as follows: functional dyspepsia 73, 83, 76 and 60%, PUD 70, 94, 91, 70% and gastric cancer 75, 95, 90 and 70%, respectively. Risk associated for the presence of PUD and gastric cancer with cagPAI genes cagE, cagT and cagM was 5.0-, 4.6- and 4.1- and 3.0-, 2.8- and 2.5-folds, respectively. Prevalence of intact cagPAI was significantly higher in PUD and gastric cancer compared to functional dyspepsia (PUD vs. functional dyspepsia, 71% vs. 38%, P = 0.01; gastric cancer vs. functional dyspepsia, 75% vs. 38%, P < 0.01). Intact cagPAI was associated with increased risk for the presence of PUD (odds ratio 5.2, 95% CI 2.4-11.3) and for the presence of gastric cancer (odds ratio 4.5, 95% CI 2.3-7.1).

CONCLUSIONS: cagPAI integrity and its different genes are linked to different forms of gastric disease and so may have a role in pathogenesis, diagnosis and management.