Molecular diagnosis of Helicobacter pylori infection and risk factor of the presence of cagA and vacA genes

Abstract

Background: Several H. pylori genes that are related to the risk of disease have been identified. The cytotoxin-associated gene (cagA) is a marker for a genomic pathogenicity (cag) island of about 40 kbp whose presence is associated with a more severe clinical outcome. A cytotoxin that injures epithelial cells is encoded by vacuolating cytotoxin A gene (vacA). vacA is present in all H. pylori strains and contains at least two variable parts. The aim of our study was to evaluate the efficiency of using PCR technique as a powerful tool besides being an easy and low cost method for diagnosis of H pylori infection through molecular detection of cagA and vacAs1 genes in gastric tissue biopsies obtained from patients diagnosed as H. pylori positive. Methods: Fifty cases were enrolled in our study that underwent endoscopy. The following investigations were done:-Paraffin-embedded tissue sections were stained (H&E) to grade the severity of gastritis to detect H. pylori as a gold standard.-CLO-Rapid urease test was carried out for all gastric biopsies.-PCR analysis for detection of cagA and vacAs1 genes in gastric tissue biopsies obtained from patients diagnosed as H. pylori positive. Results: Biochemical results: For positive histology cases, 36/41 (87.8%) were positive, while for negative histology cases, 8/9 (88.9%) were negative by rapid urease test. PCR results: For positive histology cases, 40/41 (97.6%) were positive by the PCR test for vacAs1 gene. On the other hand, out of 9 that were negative by PCR test for vacAs1 gene 9 (100%) were negative by histology. Out of 41 positive cases by histology, only 40 (97.6%) were also positive by the PCR test for cagA gene. On the other hand, out of 9 that were negative by PCR test for cagA gene 9 (100%) were negative by histology. Strong positive and statistically significant correlation between the expressions of these two genes (vacAs1 and cagA) in patient of H. pylori. (P < .000) Conclusion: We can conclude that:-Rapid urease test is good screening test when multiple biopsies are used.-Analysis of H. pylori virulence gene vacAs1 and cagA by conventional PCR method, emphasizing high sensitivity of PCR method. Abstracts for SupplementInternational Journal of Infectious DiseasesVol. 14Preview Full-Text PDF Open Archive