Tehran University of Medical Sciences Journal of Medical Bacteriology 2251-8649 4 5-6 2015 12 15 24 30 EN Hashem Fakhre Yaseri Gastroenterology, Research Center for Gastroenterology and Liver Diseases, Firoozgar Hospital, Iran University of Medical Sciences, Tehran, Iran. AND Department of Internal Medicine, Firoozgar Hospital, Iran University of Medical Sciences, Tehran, Iran. Mehdi Shakaraby Immunology Research Center, Iran University of Medical Sciences, Tehran, Iran. Hamid Reza Baradaran Department of Epidemiology, Iran University of Medical Sciences, Tehran, Iran. Seyed Kamran Soltani Arabshhi Department of Internal Medicine, Firoozgar Hospital, Iran University of Medical Sciences, Tehran, Iran. 2017 01 11 2017 01 11 Background: Helicobacter pylori strains have two classical virulence genes, the cytotoxin-associated A (cagA) gene and the vacuolating cytotoxin A (vacA) gene, which are located in the cag pathogenicity island (cagPAI). Serum immunoglobulin G (IgG) antibodies to H. pylori, especially, the CagA antigen may be a reliable marker for selection of dyspeptic patients for upper endoscopy.  Methods: Serum sample of 129 dyspeptic patients with positive H. pylori, were tested for serum IgG Anti-CagA antibody by ELISA. The presence of the cagA and vacA genotypes were determined using polymerase chain reaction (PCR) on biopsy samples taken via endoscopy.  Results: Positive serum IgG anti-CagA antibodies in patients with cagA+/vacA+ and cagA+/vacA-genotypes were 22/23 (95.6%) and 18/19 (94.7%), respectively. In addition, serum IgG anti-CagA antibodies in patients with cagA-/vacA+ and cagA-/vacA- genotypes were 22/47 (46.8%) and 33/40 (82.5%), respectively.  Conclusion: It can be concluded that the serum IgG anti-CagA antibody alone could select patients with dyspepsia following upper endoscopy. The assessment of vacuolating cytotoxin activity of H. Pylori is, therefore, not required, even when vacA gene is positive. This hypothesis needs to be studied in a large number of patients with dyspepsia. https://jmb.tums.ac.ir/index.php/jmb/article/view/245 https://jmb.tums.ac.ir/index.php/jmb/article/download/245/179