OBJECTIVETo determine vacA dominant genotypes of Helicobacter pylori in patients with peptic ulcer (PU) or chronic gastritis (CG).

METHODSH.pylori strains were isolated from mucosa samples of gastric antrum and corpus of patients suffering from PU (n=29) or CG (n=34), 126 strains of H.pylori were selected for PCR to detect s and m regions in vacA gene of the isolates. Parts of the amplification products were sequenced after T A cloning. The correlation between infection or coinfection with different vacA genotypes of H.pylori and different gastroduodenal diseases was further analyzed.

RESULTSThe positive amplification products of vacA gene, s and m regions, were found in the DNA samples of all the isolates. In these products, s1a/m1, s1a/m2, s1a/m1b and s1a/m1b m2 genotypes of vacA gene were detected and s1b and s2m1a genotypes absent. Proportions of the s1a/m1, s1a/m2, s1a/m1b and s1a/m1b-m2 genotypes were 7.1% (9/126), 61.9% (78/126), 29.4% (37/126) and 1.6% (2/126), respectively. 17.5% (11/63) of the patients were confirmed to be coinfected with different genotype H.pylori strains. No statistical differences were found in the distribution of different genotype H.pylori strain infection in the gastric diseases (P>0.05). In comparison with the reported sequences of H.pylori strain 60190 with s1a genotype and strain 87-203 with m2 genotype, homologies of the nucleotide sequences of s1a PCR products from 6 strains of H.pylori isolates and m2 PCR products from 4 strains of H.pylori isolates were 93.15% approximate, equals 94.86%and 93.63% approximate, equals 97.61%, respectively.

CONCLUSIONH.pylori with s1a/m2 or s1a/m1b are the dominant genotypes in the PU or GC patients in Zhejiang area. The nucleotide sequences of partial amplification products from the vacA dominant genotypes of H.pylori show high homology compared with the reported sequences. Part of the patients may be coinfected with different vacA genotypes of H.pylori.