Introduction: Chronic infection of H. pylori could lead to different clinical outcomes ranging from gastritis to gastric cancer. One important determinant of the outcome of H. pylori infection is bacterial genetic content which exhibits a considerable diversity. In this study, H. pylori strains which were isolated from six patients with 4-year interval were examined for genetic diversification.

Methods: Paired H. pylori isolates were obtained from gastric biopsies of six patients with 4-year interval. Bacterial isolates were characterized by polymerase chain reaction genotyping of variable 3’ region of the cagA gene and vacA alleles (s and m) using appropriate primers.

Results: All paired isolate were found to possess the cagA gene. Further examination revealed that 2 pairs of isolates display variation in 3’ Region of the cagA as well as vacA alleles. One pair had variation only in 3’region of cagA and one pair in vacA alleles. No variation was found in remaining two pairs. (details were presented in figure1)

Conclusion: results of this study showed that over a period of time, H. pylori population with different genotypes may colonize in the stomach of single host. Further studies are needed to precise determination any possible correlation between H. pylori genetic diversity and clinical outcomes of H. pylori.