High frequency of cagA and vacA s1a/m2 Genotype among Helicobacter pylori Infected Gastric Biopsies of Pakistani Children

Abstract

The vacuolating cytotoxin VacA and cytotoxin associated gene product CagA, encoded by vacA and cagA are major virulence determinants associated with pathogenesis of Helicobacter pylori. The presence and prevalence of two major H. pylori virulence associated genes among gastric biopsies of Pakistani children were investigated in the current study. Fifty one gastric biopsy specimens of children were analysed for 16S rRNA, vacA and cagA genes using PCR. The results showed that 21 (41.2%) biopsies were positive for H. pylori as determined by 16S rRNA PCR. In the 21 H. pylori positive gastric biopsies, 19 (90.5%) showed vacA s1a, 1 (4.75%) was vacA s1b and 1 (4.75%) was vacA s2 whereas, 5 (23.8%) were vacA m1 and 16 (76.2%) were vacA m2. None of the H. pylori positive biopsies carried vacA s1c subtype. The cagA gene was found in 13 (61.9%) of H. pylori infected biopsies and different vacA combinations were found with or without cagA gene. H. pylori was detected with high frequency of cagA while vacA s1a and vacA m2 regions with vacA s1a/m2 genotype were predominant in H. pylori infected gastric biopsies of children.

Analysis of Clinical Isolates of Helicobacter pylori in Pakistan Reveals High Degrees of Pathogenicity and High Frequencies of Antibiotic Resistance

“…The vacA s1a/m1 genotype was predominant among H. pylori isolates in this Pakistani cohort as compared to vacA s1a/m2, whereas the vacA s2/m2 genotype was found infrequently. This again contrasts with our previous study, in which the vacA s1a/m2 genotype was predominantly detected in H. pylori cultured from children from the same region [28]. In addition, the vacA s1b/ m2 genotype has been reported among adult patients with dyspepsia in another study from the same region [44].…”

“…This percentage was higher than in our recent previous report from the same geographic area. This reported 61.9% prevalence of the cagA gene in H. pylori detected in gastric biopsy specimens, but these were collected from children [28]. Other studies from the same region of Pakistan have shown 24.2% [44] and 56% [45] cagA prevalence in adult dyspeptic patients.…”

“…Total genomic DNA was extracted from all H. pylori isolates by ethanol precipitation and proteinase K treatment, using a modification of a method previously described [28]. Briefly, a single bacterial colony was selected, resuspended in 20 µL of 1% sodium dodecyl sulfate, 40 µL proteinase K (100 µg/mL), 80 µL of proteinase K buffer (4M NaCl, 0.5M EDTA; pH 7.5), and incubated at 55 °C for 1 hour.…”

Prevalence and Correlation with Clinical Diseases ofHelicobacter pylori cagAandvacAGenotype among Gastric Patients from Northeast China

“…Rasheed et al reported high frequency of cagA (61.9%) with predominant vacA s1a/m2 genotype in H. pylori infected gastric tissues of Pakistani children [37]. A previous study reported significantly higher percentages of cagA -positive and vacA s1 and vacA m1 genotypes with high risk for GC [39].…”

“…The neighboring countries of China were also reported to have high prevalence of cagA ; for example, India has high cagA prevalence of 96.2% [ 26 ]. Rasheed et al reported that 52% of H. pylori strains carried cagA gene with the positivity rate of 80% in GC, 74% in GU, 63% in duodenal ulcer (DU), and 11% in normal cases from Pakistan [ 37 ]. Conversely, in Western Europe, cagA -positive strains are less prevalent and more frequently found in GU or GC patients [ 38 ].…”