Prevalence of Helicobacter pylori pathogenicity-associated cagA and vacA genotypes among Pakistani dyspeptic patients.

The cytotoxin-associated gene A (cagA), and the vacuolating cytotoxin gene A (vacA) products are considered the most important pathogenic determinants of Helicobacter pylori, a gram-negative bacterium causing gastrointestinal disorders such as duodenal ulcers, gastritis and mucosa-associated lymphoid tissue disease. A higher prevalence of H. pylori has been reported in various regions in the Pakistani population; however, no data are available about the virulence-associated genetic determinants. The objective of this study was to determine the prevalence of virulence-associated genes, cagA, vacA and particularly vacA allelic variants among dyspeptic patients from Pakistan. Gastric biopsy samples were obtained from 78 adult patients presenting dyspepsia symptoms. DNA was isolated and analyzed for the presence of H. pylori and its genotypes by PCR. Genus-specific PCR involving 16S rRNA gene revealed that 66 of the 78 patients were positive for H. pylori, an overall prevalence of 84.6% for this particular study. The most common vacA genotype was s1b/m2 (54.5%) followed by s1a/m1 (19.7%). cagA was positive in 24.2% of the cases and strongly associated with s1a/m1, vacA. The prevalence of virulent cagA, and vacA allelic form s1a/m1 was lower than that reported from neighboring countries.