:: Volume 3, Issue 3 (Autumn 2013) ::
JABS 2013, 3(3): 208-214 Back to browse issues page
Isolation, Characterization and Antibiotic Resistance of Shiga Toxin-Producing Escherichia coli in Hamburger and Evolution of Virulence Genes stx1, stx2, eaeA and hly by Multiplex PCR
Mohammad Kargar 1, Peyman Dianati, Maryam Homayoon, Houshang Jamali
1- , mkargar@jia.ac.ir
Abstract:   (24892 Views)
Background & Objectives: Shiga toxin-producing Escherichia coli (STEC) O157:H7 have emerged as pathogens that can cause food-borne infections and severe and potentially fatal illnesses in humans. E.coli O157:H7 colonizes the digestive tract of cattle and is transmitted to humans by food and water. The objectives of this study were to characterize the prevalence of E.coli O157:H7 isolates in hamburger in Shiraz and to test their antimicrobial sensitivity.
Material & Methods: In this research, 428 samples of hamburger were collected from 7 main factories of meat products and enriched in TSB with novobiocin medium at 37ºC. Fermentation of sorbitol and lactose and activities of β- glucuronidase of separated bacteria were examined by using the SMAC and VRBA media and CHROMagar medium. Then isolation of E.coli O157:H7 was confirmed with the use of specific antisera and with the multiplex PCR method, the presence of E.coli O157:H7 virulence genes – including stx1, stx2, eaeA, and hly – was analyzed. Finally, antibiotic resistance strains were tested with disk diffusion methods.
Results: Out of all the examined samples, 264 (61.68%) sorbitol-negative bacteria were separated in the CT-SMAC medium. After evaluation with specific antisera, the rate of the recognition of E.coli O157:H7 was 5 (1.17%). The stx1 and eaeA genes were diagnosed in 2 (0.47%) cases of these samples. All the isolated bacteria were resistant to penicillin, clindamycin, and erythromycin antibiotics.
Conclusion: The presence of STEC in animal products suggests that they may be a potential hazard for human health. A regular monitoring of STEC O157, mainly in hamburger, should be performed to prevent a possible consumer health threat.
Keywords: Hamburger, Shiga toxin-producing E.coli, Antibiotic resistance, Virulence gene, Multiplex PCR
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Type of Study: Research | Subject: Genetics
Received: 2013/04/4 | Accepted: 2013/08/9 | Published: 2013/09/23

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Volume 3, Issue 3 (Autumn 2013) Back to browse issues page