Helicobacter pylori Pathogenicity-Associated cagA and vacA Genotypes Among Nigerian Dyspeptic Patients
Objective: Although Helicobacter pylori infection is endemic in Nigeria, the specific genotypes that influence treatment responses are scarcely known. We aimed to determine the specific genotypes of H. pylori virulence genes, vacA and cagA in dyspeptic patients.
Subjects and methods: Gastric biopsy samples were obtained from 80 dyspeptic patients referred for endoscopy. Genomic DNA was extracted from biopsies using the ReliaPrep DNA kit. H. pylori DNA was detected by a singleplex PCR based on the genus specific 16s rRNA gene. The vacA subtypes for the s1 and s2 regions and the m1 and m2 alleles were detected by allele specific multiplex PCR. The cagA gene was amplified by a singleplex PCR.
Results: Of the 80 samples, 30 (37.5%) had abnormal mucosa which were chronic gastritis. The rest (62.5%) had normal mucosa lining. Of the 30 chronic gastritis cases, 22 (73%) had H. pylori infection as detected by 16s rRNA PCR. Only 2 (4%) of the normal mucosa cases had H. pylori infection. For the vacA genotypes, 79% of the H. pylori infections were s1c/m2 genotype, followed by 8% s1b/m2 genotype. Three different genotypes: s1c/m1/m2, s1c/s2/m2 and s1c/m1 occurred at 4% each. The most virulent vacA genotype, s1/m1 was only 8% while the least virulent vacA genotype s2/m2 was 4%. The moderate virulent vacA genotype, s1/m2 was the most prevalent (83%) in the Nigerian patients. The most prevalent subtype was the s1c/m2. Only 7 cases (29%) were cagA positive.
Conclusion: The pathogenicity-associated virulence genes present in Nigerian dyspeptic patients were moderate types. The endemicity of the disease may not necessarily lead to high rate of fatal outcomes or treatment failures as reported in other parts of the world.