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The Scientific World Journal
Volume 2012, Article ID 231342, 13 pages
Research Article

Molecular Characterization of Shiga Toxin-Producing Escherichia coli Isolated from Ruminant and Donkey Raw Milk Samples and Traditional Dairy Products in Iran

1Department of Microbiology, College of Veterinary Medicine, Islamic Azad University, Shahrekord Branch, Shahrekord 166, Iran
2Young Researchers Club, Islamic Azad University, Shahrekord Branch, Shahrekord 166, Iran
3Department of Food Hygiene, College of Veterinary Medicine, Islamic Azad University, Shahrekord Branch, Shahrekord 166, Iran
4Young Researchers Club, Islamic Azad University, Jahrom Branch, Jahrom 74135-355, Iran

Received 6 May 2012; Accepted 4 July 2012

Academic Editors: Y.-Y. M. Chen, M. Dunn, V. Fedorenko, and J. L. Romalde

Copyright © 2012 Hassan Momtaz et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The aims of the current study were to detect the virulence factors and antibiotic resistance of Shiga toxin-producing E. coli, in animal milk and dairy products in Iran. After E. coli dentification with culture method, PCR assay were developed for detection of pathogenic genes, serotypes and antibiotic resistance genes of E. coli. Results showed that out of 719 samples, 102 (14.18%) were confirmed to be positive for E. coli and out of 102 positive samples, 17.64% were O26 and 13.72% were O157 and 1.96% were O91 and 1.96% were O145 serotypes. Totally, the prevalence of stx1 and papA genes were the highest while the prevalence of sfaS and fyuA were the lowest in the positive samples. PCR results showed that tetA, tetB were the highest (64.70%) and aac(3)-IV were the lowest (27.45%) antibiotic resistant genes in E. coli positive samples. Our study indicated that the isolated E. coli trains in these regions had a highest antibiotic resistance to tetracycline (58.82%) and the lowest to nitrofurantoin (3.92%). tetA gene and E. coli O157 serotype had highest and aac(3)-IV gene, and E. coli O145 serotype had a lowest frequency rates of antibiotics resistance genes, in the region.