Isolation of Helicobacter pylori and Genotyping the Isolates Based on cagA and vacA Virulence Genes

In this study, we aimed to isolate and genotype H. pylori strains from gastric biopsies of patients having gastroduodenal complaints. Our isolation rate was 32.8% (64/21),suggesting that culture was a relatively weak diagnostic tool for H. pylori infection. We used multiplex PCR to identify the cagA, vacA s1/s2, and vacA m1/m2 genotypes. Our results indicated that 71.4% of the strains were both cagA-positive and cagA-negative. The predominant vacA genotype was s1/m1 (100%), followed by s1/m2 (62.5%). Only one isolate was s2/m2, as expected, since samples were obtained from patients with clinical symptoms. In terms of allelic vacA combinations, in cagA+ samples, 9 (42.8%), 5 (23.8%), and 1(4.8%) strains carried s1/m1, s1/m2, and s2/m2 genotypes, respectively. None of the cagA- strain was determined to have s1/m1 vacA genotype. However, s1/ m2 and s2/m2 vacA genotypes were found equally (14.3%) in this group. The association between s1/m1 vacA genotype and cagA status was found statistically significant (P<0.05).