genotype but not or increase the risk of ulcer and gastric cancer in patients from Southern Mexico.

Background: The , and genotypes of are associated with gastric pathology. The objectives were to determine the frequency of infection and distribution of the , and genotypes of in patients with gastric ulcer, chronic gastritis and gastric cancer, and to evaluate the association of virulent genotypes with diagnosis.

Methods: We studied 921 patients with symptoms of dyspepsia or with presumptive diagnosis of gastric cancer. The DNA of and the , and genes was detected by PCR in total DNA from gastric biopsies. The association of and of its , and genotypes with diagnosis was determined by calculating the odds ratio (OR).

Results: Chronic gastritis was confirmed in 767 patients, gastric ulcer in 115 and cancer in 39. The prevalence of was 47.8, 49.6 and 61.5% in those groups, respectively. was more frequent in the surrounding tissue (69.2%) than in the tumor (53.8%). The genotype predominated in the three groups (45.2, 61.4 and 83.3%, respectively). was associated with cancer (OR = 2.08; 95% CI 1.05-4.13;  = 0.035) but not with ulcer (OR = 1.07; 95% CI 0.71-1.61;  = 0.728). The genotype was associated with ulcer and cancer (OR = 2.02; 95% CI 1.12-3.62;  = 0.019 and OR = 6.58; 95% CI 2.15-20.08;  = 0.001, respectively). was associated with gastric cancer, and was not associated with the diagnosis.

Conclusions: In population from Southern Mexico, and the genotype were associated with gastric cancer and the /+/+ strains predominated in tumor and adjacent tissue.