AIM:To evaluate the prevalence of Helicobacter pylori(H.pylori ) babA2 ,babB and a recombinant gene between babA2 and babB(babA2/B ),and their role in the development of atrophic gastritis in Costa Rican and Japanese clinical isolates.METHODS:A total of 95 continuous H.pylori-positive Costa Rican(41 males and 54 females;mean age,50.65 years;SD,± 13.04 years) and 95 continuous H.pylori-positive Japanese(50 males and 45 females;mean age,63.43;SD,± 13.21 years) patients underwent upper endoscopy from October 2005 to July 2006.They were enrolled for the polymerase chain reaction(PCR)-based genotyping of the H.pylori babA2 ,babB and babA2/B genes.Statistical analysis was performed using the χ2 test and the Fisher’s exact probability test and multivariate analysis was performed by logistic regression adjusting for gender and age.P < 0.05 was regarded as statistically significant.RESULTS:The PCR-based genotyping of 95 Costa Rican and 95 Japanese isolates showed a higher prevalence of babA2 in Japan(96.8%) than in Costa Rica(73.7%),while that of babA2/B was higher in Costa Rica(11.6%) than in Japan(1.1%).In Costa Rican isolates only,babA2 was significantly associated with atrophic gastritis(P = 0.01).CONCLUSION:These results suggest that the status of babA2 and babA2/B shows geographic differences,and that babA2 has clinical relevance in Costa Rica. AIM: To evaluate the prevalence of Helicobacter pylori (H. pylori) babA2, babB and a recombinant gene between babA2 and babB (babA2 / B), and their role in the development of atrophic gastritis in Costa Rican and Japanese clinical isolates. METHODS: A total of 95 continuous H. pylori-positive Costa Rican (41 males and 54 females; mean age, 50.65 years; SD, ± 13.04 years) and 95 continuous H. pylori-positive Japanese (50 males and 45 females; 63.43; SD, ± 13.21 years) patients underwent upper endoscopy from October 2005 to July 2006. They were enrolled for the polymerase chain reaction (PCR) -based genotyping of the H.pylori babA2, babB and babA2 / B genes.Statistical analysis was performed using the χ2 test and the Fisher’s exact probability test and multivariate analysis was performed by logistic regression adjusting for gender and age. P <0.05 was regarded as significant significant .RESULTS: The PCR-based genotyping of 95 Costa Rican and 95 Japanese isolates showed a higher prevalence of babA2 in Costa Rica (73.7%), while that of babA2 / B was higher in Costa Rica (11.6%) than in Japan (1.1%). In Costa Rican isolates only, babA2 was significantly associated with atrophic gastritis (P = 0.01) .CONCLUSION: These results suggest that the status of babA2 and babA2 / B shows geographic differences, and that babA2 has clinical relevance in Costa Rica.