Differences in virulence markers between Helicobacter pylori strains from the Brazilian Amazon region.

INTRODUCTION This study compares virulence markers of Helicobacter pylori isolated from patients in 2 cities in the Brazilian Amazon. METHODS The study analyzed 168 patients with chronic gastritis from Belém and 151 from Bragança, State of Pará, Brazil. Levels of bacterial DNA associated with cagA and vacA alleles were checked by PCR, and hematoxylin-eosin staining was used for histologic diagnosis. RESULTS In Bragança 87% of patients were genotype s1m1 cagA-positive (s1m1 cagA+), compared with 76% in Belém. In samples from patients in both cities, there was an association between s1m1 cagA+ strains and gastric mucosal damage. CONCLUSIONS Both cities have a high frequency of s1m1 cagA+ strains of H. pylori.