Surveillance and clinical relevance of vacA genotypes of Helicobacter pylori infecting dyspeptic patients in mid-Essex

Abstract

The Helicobacter pylori vacuolating cytotoxin is a putative pathogenicity factor encoded by vacA, a mosaic gene with a global distribution. The vacA type prevalence and diversity of H. pylori isolated from antral gastric biopsies of 360 dyspeptic patients in mid-Essex, and of 79 patients from other locations, were investigated in order to test for links with disease severity. Mid (m)-region genotyping and subtyping by vacA HaeIII RFLP (restriction fragment length polymorphism) analysis showed that the m1 and m2 alleles were diverse, with 191 different subtypes. Variation in 44% of strains was accounted for by ten subtypes of which subtype v-1 represented a conserved core (33%) of the m1 form. Prevalence rates for combined mid and signal (s)-region genotypes were 40% for s1/m1, 46% for s1/m2, and 11% for s2/m2. Overall, vacA genotyping provided high typability and discrimination, but no specific RFLP markers could reliably predict a clinically significant presentation due to an H. pylori infection.