High frequency of gastric colonization with multiple Helicobacter pylori strains in Venezuelan subjects

Abstract

Multiple Helicobacter pylori strains may colonize an individual host. Using enzyme-linked immunosorbent assay and line probe assay (LiPA) techniques, we analyzed the prevalence of mixed H. pylori colonization in 127 subjects from Venezuela, a country of high H. pylori prevalence, from three regions representing different population groups: the Andes (Merida), where Caucasian mestizos predominate, a major city near the coast (Caracas), where Amerindian-Caucasian-African mestizos predominate, and an Amazonian community (Puerto Ayacucho), where Amerindians predominate and mestizos reflect Amerindian and Caucasian ancestry. Among 121 H. pylori-positive persons, the prevalence of cagA-positive strains varied from 50% (Merida) to 86% (Puerto Ayacucho) by LiPA. Rates of mixed colonization also varied, as assessed by LiPA of the vacA s (mean, 49%) and m (mean, 26%) regions. In total, 55% of the individuals had genotypic evidence of mixed colonization. vacA s1c, a marker of Amerindian (East Asian) origin, was present in all three populations, especially from Puerto Ayacucho (86%). These results demonstrate the high prevalence of mixed colonization and indicate that the H. pylori East Asian vacA genotype has survived in all three populations tested.

FIG. 1.

Sensitivity analysis of R-M system alleles for detecting mixed colonization using genomic DNA. For the positive control, the template DNA (T) is 100 ng of homologous genomic DNA. For one negative control, competing heterologous DNA (C) was used at 100 ng. For each reaction, template DNA at 100 ng, 10 ng, 1 ng, 0.1 ng, 0.01 ng, or 0.001 ng was added to 100 ng of competing DNA. Another negative control included water (W) only.

FIG. 2.

Agarose gel electrophoresis of PCR products involving the hpyI (locus 1) and hpyIII (locus 2) R-M loci in gastric biopsies from patients M20 and M67. Lanes indicate PCR products or their absence at each locus. Primers amplified hpyIR and/or hrgB at locus 1 and hpyIIIR and/or hrgA at locus 2. In both patients, there is evidence for at least two different strains in each gastric biopsy.