Helicobacter pylori virulence genes of minor ethnic groups in North Thailand

BACKGROUND There are few studies analyzed concurrently the prevalence and genotypes of Helicobacter pylori infection with the ancestor origins from different ethnics, especially with including minority groups. We recruited a total of 289 patients in MaeSot, Thailand (154 Thai, 14 Thai-Chinese, 29 Karen and 92 Hmong ethnics). The virulence genes and genealogy of the strains were determined by PCR-based sequencing. RESULTS Based on culture and histology/immunohistochemistry, the prevalence of H. pylori infection was 54.5% (158/289). Among 152 isolates cultured, the East-Asian-type cagA was predominant genotype among strains from Hmong, Thai-Chinese and Thai (96.0% [48/50], 85.7% [6/7] and 62.7% [47/75], respectively), whilst majority of strains from Karen had Western-type cagA (73.3% [11/15]). Patients infected with the East-Asian-type cagA strains had significantly higher activity and intestinal metaplasia in the antrum and activity in the corpus than those with Western-type cagA (P = 0.024, 0.006 and 0.005, respectively). The multilocus sequencing typing analysis discriminated that most strains from Hmong and Thai-Chinese belonged to hspEAsia (92.0 and 85.7%, respectively), whereas strains from Karen predominantly possessed hpAsia2 (86.7%) and strains from Thai were classified into hspEAsia (45.2%) and hpAsia2 (31.1%). CONCLUSIONS Helicobacter pylori genotypes were relatively different among ethnic groups in Thailand and were associated with the source of ancestor even living in a small rural town. Caution and careful check-up are required especially on Hmong ethnic associated with high prevalence of virulence genotypes of H. pylori.