Association of CagA and VacA genotypes of helicobacter pylori with gastroduodenal diseases

ABSTRACT

Helicobacter pylori [H. pylori] infects the majority of the population in developing countries. However, the rate of gastrointestinal complications has no parallel with the infection. In the present study our aim was to detect and type the cagA [cytotoxin associated gene] status and the vacA [vacuolating cytotoxin] genotypes directly from biopsy DNA, and to further define the relationship between H. pylori genotypes and gastroduodenal pathology. Antral gastric biopsies were obtained for molecular analysis and histopathological diagnosis from 105 patients with dyspeptic symptoms undergoing upper gastrointestinal endoscopy. H. pylori DNA, cagA status and vacA s and m types were detected by polymerase chain reaction [PCR]. H. pylori DNA was detected in 100 [95.2%] of gastric biopsy specimens, of those, 43 [43%] were cagA positive and all [100%] were vacA positive. The vacA s2/m2 genotype was the most prevalent [54%] followed by s1/m2 [27%], then s1/m1 [16%] and 3% showed multiple genotypes. We found 90.5% and 75% of cases with peptic ulcer disease [PUD] and gastric adenocarcinoma respectively to be cagA positive in contrast to only 28% of gastritis cases. The vacA s1 allele was the commonest in PUD and gastric adenocarcinoma cases [85.7% and 75% respectively], while the vacA s2 allele was the commonest in gastritis cases [70.7%]. In conclusion, we suggest the possibility of a genotype-phenotype association of H. pylori disease. Determination of cagA status and vacA genotypes may contribute to the potential clinical identification of patients at different levels of risk. We recommend further studies involving other virulence genes