Reciprocal impact of host factors and Helicobacter pylori genotypes on gastric diseases

AIM: To assess the impact of Helicobacter pylori(H. pylori) genotypes and patient age and sex on the development of gastric diseases.METHODS: H. pylori-infected patients(n = 233) referred to the endoscopy unit at Tehran University of Medical Sciences(Tehran,Iran) were diagnosed with chronic gastritis(CG),gastric ulcer(GU),or duodenal ulcer(DU). Brucella blood agar was used for biopsy cultures and H. pylori isolation under microaerobic conditions. H. pylori isolates were confirmed with biochemical tests and through amplification of the 16 S r RNA gene. DNA was extracted from fresh cultures of the H. pylori isolates and used for amplification of vac A alleles and the cag A gene. Statistical analysis was performed to determine the association between H. pylori genotypes,age(< 40 years vs > 40 years) and sex of the patient,and gastric diseases.RESULTS: CG was the most prevalent gastric disease(113/233; 48.5%),compared to GU(64/233; 27.5%)and DU(56/233; 24%). More patients were male,and gastric diseases were more frequent in patients > 40 years(P < 0.05). The percentage of CG and GU patients that were male and female did not show a significant difference; however DU was more common in males(P < 0.05). Interestingly,a diagnosis of CG in patients > 40 years was more common in females(18.5%) than males(11.6%)(P = 0.05),whereas a diagnosis of GU or DU in patients > 40 years was more frequent in males(14.6% vs 10.7% and 12.4% vs 4.3%,respectively). Overall,genotyping of the H. pylori isolates revealed that the vac A s1(82%),vac A m2(70%),and cag A+(72.5%) alleles were more frequent than vac A s2(18%),vac A m1(29.2%),and cag A-(all P < 0.05). The vac A s1m2 cag A+ genotype was the most prevalent within the three disease groups. vac A s1m2 frequency was 56.2% with a similar occurrence in all diagnoses,while vac A s1m1 appeared more often in DU patients(33.9%). A genotype of vac A s2m2 occurred in 15% of isolates and was more common in CG patients(21.2%); vac A s2m1 was the least common genotype(3%). The vac A s1 allele was found to be a risk factor for DU,vac A s2 for CG,and vac A s1 and vac A s2 for GU(all P < 0.05). The vac A s2m2 genotype was associated with the development of CG and GU compared to DU(P < 0.05). No correlation was found between vac A m or cag A and gastric diseases.CONCLUSION: The outcome of H. pylori infection is the result of interaction between bacterial genotypes and the age and sex of infected individuals.