Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 5 1 2013 03 15 42 47 EN Mohammad-Yousef Alikhani Department of Microbiology, Faculty of Medicine, Hamadan University of Medical Sciences, Hamedan, Iran. Seyyed-Hamid Hashemi Department of Infectious diseases, Faculty of Medicine, Hamedan University of Medical Sciences, Hamedan, Iran. Mohammad-Mehdi Aslani Department of Microbiology, Pasteur Institute of Iran, Tehran,Iran. Safar Farajnia Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran. 2015 10 16 Background and Objectives: Pathogenic strains of Escherichia coli are a common cause of acute infectious diarrhea. The aim of this study was to investigate the frequency, virulence markers and antibiotic resistance patterns of diarrheagenic E. coli (DEC) isolated from adolescents and adults in Hamadan, west of Iran. Materials and Methods: A total of 187 stool samples were collected from adults with acute diarrhea. Stool culture was performed by conventional methods for enteropathogenic bacteria. Virulence factor genes for DEC were detected by polymerase chain reaction. Antimicrobial susceptibility was tested using the disk diffusion method. Results: Among the 187 patients, 40 (21.4%) were positive for DEC. The most frequently identified DEC was enteropathogenic E. coli (47.5%), followed by enteroaggregative (20%), enterotoxigenic (17.5%) and shiga-toxin producing E. coli (15%). No isolates of enteroinvasive E. coli were detected. All STEC strains were stx+ / eaeA-. Out of the seven ETEC strains, five (71.4%) produced ST, one (14.3%) produced only LT and one (14.3%) of the isolates produced both ST and LT encoded by est and elt genes, respectively. Among the 40 DEC strains 27(67.5%) were multidrug resistant. Conclusion: DEC contribute to the burden of diarrhea in adults in Hamadan. Enteropathogenic E. coli was the most commonly identified DEC strain in the region studied. https://ijm.tums.ac.ir/index.php/ijm/article/view/661 https://ijm.tums.ac.ir/index.php/ijm/article/download/661/433