Objective: To investigate the prevalence of cytotoxin associated gene (cag A) and vacuolating cytotoxin gene (vac A) subtypes of Helicobacter pylori (Hp) from patients with upper gastrointestinal diseases in Guangzhou, and to assess the relationship between cag A, vac A subtypes and Hp related gastrointestinal diseases.
Methods: 191 Hp strains were isolated from patients with different gastrointestinal diseases in Guangzhou. Bacterial DNA from all these strains was extracted. cag A and vac A alleles were typed using PCR with specific primers.
Results: In Guangzhou, Hp cag A positive rate was 85.3% (163/191). cag A positive rate was significantly higher in gastric cancer and peptic ulcer than that in chronic gastritis (P < 0.05). There were six vac A mosaicisms, including 168 for s1a/m2 (88.0%), 14 for s1a/m1b (7.3%), 6 for s1b/m2 (3.1%), 1 for s1b/m1b (0.5%), 1 for s2/m2 (0.5%) and 1 for s1a/m1b-m2 (0.5%). The rate of vac A s1a/m2 subtype in chronic gastritis, peptic ulcer and gastric carcinomas was 87.5% (70/80), 87.5% (84/96) and 93.3% (14/15) respectively. There was no significant relationship between cag A and vac A subtypes (P > 0.05).
Conclusion: cag A(+) and vac A s1a/m2 subtype of Hp is predominant in patients with upper gastrointestinal diseases in Guangzhou, cag A(+) strains are further more common in patients with gastric cancer and peptic ulcer.