Prevalence and Virulence Genotypes of Helicobacter pylori in Patients with Gastric Cancer: A Cross-Sectional Study

Background: Helicobacter pylori virulence genotypes cagA and vacA are associated with gastric carcinogenesis risk, yet Bangladeshi data linking these genotypes to confirmed gastric cancer remain scarce. Objective: This study examined the prevalence of cagA and vacA genotypes and their association with each other among patients with histologically confirmed gastric cancer at a tertiary Bangladeshi center. Methods: In this cross-sectional study, 63 patients with histologically confirmed gastric malignancy underwent upper gastrointestinal endoscopy at Bangabandhu Sheikh Mujib Medical University and ICDDR,B (July 2009-January 2011); antral and corpus biopsies were genotyped for cagA and vacA (s1/s2, m1/m2) by multiplex PCR. Associations between cagA status and vacA genotypes were assessed among H. pylori-positive patients only (n=33) using Fisher's exact test, with a Bonferroni-adjusted threshold (p<0.00625) applied given eight comparisons. Results: Participants were predominantly male (79.4%, n=50) with the largest age group in the 41-50-year band (39.7%, n=25). H. pylori DNA was detected in 33/63 patients (52.4%). Among the 33 positive patients, cagA was present in 22 (66.7%) and vacA in 100% (33/33). vacA s1 predominated (73%), followed by m1 (54%) and m2 (45%), with s2 least common (30%). The s1m1 allelic combination was most frequent (42%), followed by s1m2 (27%) and s2m2 (18%); s2m1 was rarest (12%). After correction of a denominator error, recalculated Fisher's exact tests showed that cagA positivity was significantly associated with vacA s1 (95.5% vs 27.3%, p=0.0001) and s2m2 negativity (0% vs 54.5%, p=0.0004), both remaining significant after Bonferroni correction. The association with s1m1 was nominally significant (59.1% vs 9.1%, p=0.0089) but did not meet the Bonferroni-adjusted threshold (p<0.00625). Associations with m1, m2, s1m2, and s2m1 were not statistically significant after correction. Conclusion: In this cross-sectional cohort, cagA-positive H. pylori strains were significantly associated with vacA s1 and with vacA s2m2 negativity; the association with s1m1 was attenuated after correcting for multiple comparisons. These findings describe genotype co-occurrence patterns rather than a causal or progression-driving relationship, and should be interpreted in light of the modest H. pylori-positive subgroup size (n=33).