Prevalence ofHelicobacter pyloripathogenicity-associatedcagAandvacAgenotypes among Pakistani dyspeptic patients

Abstract

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.

Prevalence, diversity and disease association of Helicobacter pylori in dyspeptic patients from Pakistan

“…Our report and another from Yakoob et al confirm the decreasing trend of H. pylori infection overtime in Karachi, which is comparable to trends seen in other South Asian and European countries [44][45][46]. Interestingly, earlier studies from northern and central parts of Pakistan reported 66% and 84% prevalence rates among dyspeptic patients [25,29], indicating the difference in H. pylori infection in geographic niches and ethnic groups in Pakistan. Interestingly cagA gene analysis further confirms the above-mentioned observation.…”

“…Several studies reported the high rate of H. pylori infection in the country based on serological, bacteriological, and histological observations [25][26][27]. Recent reports, however, document the prevalence of the vacA s1m1 genotype in Pakistan, endorsing the common trend of other South Asian neighbors [28,29]. The presence of the organism in drinking water has also been reported, indicating greater chances of infection for the community [30,31].…”

Helicobacter pylori genotypes among patients in a university hospital in Egypt: identifying the determinants of disease severity

“…22 The distribution of vacAs1a and vacAs1b varies also between different areas in the same country, as in Pakistan and Chilli. 23,24 Contradictory to studies demonstrating a higher risk for development of peptic ulcer disease upon gastric infection with H. pylori strains containing type vacAs1 allele/subtypes 25 , we found that this correlation is non-significant, as shown in table 3. A similar finding has also been concluded from eastern Asia 26 , Iraq and Iran.…”

Presence of Helicobacter pylori in drinking water of Karachi, Pakistan

“…Increased rates of H. pylori infection in developing nations such as Pakistan, Vietnam, Bangladesh and India, which combat poverty, poor sanitary conditions and overcrowding, indicate the role of environmental factors in the transmission of infection [17][18][19][20]. In 2007, Ahmed et al indicated that the risk of H. pylori infection can be reduced by improving personal hygiene and regular use of boiled drinking water [20].…”