Benefits of Helicobacter pylori cagE genotyping in addition to cagA genotyping: a Bulgarian study

Abstract

Associations of Helicobacter pylori cagE status with complex patient characteristics remain to be elucidated in Eastern Europe. The aim of this study was to assess the frequencies of cagE gene and cagA/cagE combinations in H.pylori strains from symptomatic Bulgarian patients and to improve cagA detection. cagA and cagE genotypes were evaluated in 219 patients with single-strain infections. In total, 84.9% of strains were cagA (+), while 68.5% were cagE (+). cagA (+), cagE (+), and cagA (+)/cagE (+) strains were more prevalent in peptic ulcer (93.8%, 84.4%, and 84.4%) compared with nonulcer patients (81.3%, 61.9%, and 61.3%, respectively). In elderly patients, cagE (+) and cagA (+)/cagE (+) strains were 1.9-fold more common than in the 12 children evaluated. Only 10% of the elderly subjects harbored low-virulence cagA (+)/cagE (-) strains compared with 16.8% of adults and 41.7% of children. Intriguingly, prevalence of the cagA (+)/cagE (-) genotype was 2.1-fold lower in men than in women, suggesting a higher frequency of more virulent strains in men. The presence of both cag genes and combinations was not linked to strain susceptibility to clarithromycin or metronidazole, place of residence, or prior therapy. Use of an extra primer pair increased cagA detection in 14.7% of 31 cagA (-) strains. In conclusion, use of a second primer pair for the cagA gene can be recommended in countries with common cagA (+) strains. Although both cag genes were linked to severe diseases in Bulgarian patients, the best discrimination of virulent strains was obtained by the cagA/cagE combination or by the cagE gene alone. cagE prevalence increased gradually with patient age, while the cagA (+)/cagE (-) genotype, implying a disrupted cag pathogenicity island, was associated with both younger age and female gender.