en Medical Bacteriology Medical Bacteriology Original Research Original Research <p><strong>Background: </strong>Helicobacter pylori (H. pylori or Hp) has been strongly associated with the peptic ulcer diseases, chronic gastritis, ulcers, and gastric cancer. Genes associated with pathogenicity have been designated for H. pylori, and some of them appear to be related to more severe clinical consequences of the infection. The present study was conducted to determine cagA, vacA, cagE, iceA1, oipA, and iceA2 genes in H. pylori strains isolated from gastroduodenal patients, who referred to Shariati hospital in Tehran, Iran.<br> <strong>&nbsp;&nbsp; Methods:</strong> Gastric biopsy specimens were collected during endoscopy from patients, who referred to the Shariati hospital in Tehran, Iran during January and November 2015. After isolation of H. pylori from the biopsy culture, genomic DNA was extracted and subsequently used to identify H. pylori and virulence genes using specific primers.<br> <strong>&nbsp;&nbsp; Results:</strong> The isolation rate of H. pylori strains was 65.7% (169/257). The frequency of cagA, vacA, cagE, iceA1, oipA, and iceA2 was 143 (% 84.6), 169 (100%), 131 (77.5%), 97 (57.3%), 89 (52.6%), and 72 (42.6%), respectively.<br> <strong>&nbsp;&nbsp; Conclusion:</strong> In this study, a significant difference was observed between investigated genes and strains isolated from PUD and GC patients (p<0.05).<br> &nbsp;<br> &nbsp;</p> Helicobacter pylori, Iran, Virulence factors, Multiplex PCR, Duodenal ulcers 555 559 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-3164-2&slc_lang=en&sid=1 Yasaman Saeidi Saeidiy@yahoo.com 200319475328460034194 200319475328460034194 No Department of Microbiology, Tonekabon Branch, Islamic Azad University, Tonekabon, Iran. Abazar Pournajaf Abazar_Pournajaf@yahoo.com 200319475328460034195 200319475328460034195 No Department of Microbiology, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran. Mehrdad Gholami mehrdad_gholami90@yahoo.com 200319475328460034196 200319475328460034196 No Department of Microbiology, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran. Meysam Hasannejad-Bibalan Bibalan.m@yahoo.com 200319475328460034197 200319475328460034197 No Department of Microbiology, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran. Sajjad Yaghoubi Sajjad_Yaghoubi@yahoo.com 200319475328460034198 200319475328460034198 No Division of Microbiology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. Mahmoud Khodabandeh Mahmoud.Khodabandeh@yahoo.com 200319475328460034199 200319475328460034199 No Department of Pediatric Infectious Disease, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran. Behzad Emadi Behzad_Emadi@yahoo.com 200319475328460034200 200319475328460034200 No Department of Microbiology, School of Medicine, Iran University of Medical Sciences, International campus, Tehran, Iran. Elaheh Ferdosi-Shahandashti Shahandashti66@yahoo.com 200319475328460034201 200319475328460034201 No Department of Medical Biotechnology, Faculty of Medicine, Babol University of Medical Sciences, Babol, Iran. Ramazan Rajabnia : ramazan69@yahoo.com 200319475328460034202 200319475328460034202 Yes Infectious Diseases and Tropical Medicine Research Center, Babol University of Medical Sciences, Babol, Iran.