DNA-Level Characterization of Helicobacter pyloriStrains from Patients with Overt Disease and with Benign Infections in Bangladesh

ABSTRACTThe complex relation between the genotype of Helicobacter pyloriand its association with clinical outcome is not well understood. Studies in the West have showed that strains expressing certain virulence factors (vacAs1, vacAm1, and cagA) are associated with duodenal ulcer disease. However, the H. pylorigenotype is known to vary with geographic region. In the present study, we compared several virulence markers (cagA, vacA, and iceA) and neutral markers (IS605, IS606, and IS608) in H. pyloristrains isolated from 65 adult patients with peptic ulcer (PU) and 50 patients with nonulcer dyspepsia (NUD). PCR tests indicated that cagAis present in 75% of the strains from patients with PU compared to 55% in patients with NUD, and 80% of the isolates from patients with PU carried potentially toxigenic vacAs1alleles of the vacuolating cytotoxin gene (vacA) compared to 60% in isolates from patients with NUD. However, no significant difference in any other virulence marker was observed in isolates from both groups. Phylogenetic analysis of the vacAmiddle region and the 5' end of the cagAgene indicates that Bangladeshi isolates are more closely related to H. pyloriisolates from India and are different from isolates from East Asia.