Evaluation of virulance genes of Shiga toxin producing Escherichia coli from Juice Purchase and vegetables in Shiraz

Subject Areas : Food Microbiology

Marjan Shah Illi ¹ , Mohammad Kargar ² , Abbasali Rezaeian ³ , Maryam Homayoon ⁴ , Mehdi Kargar ⁵ , Sadegh Ghorbani-Dalini ⁶

1 - Department of Microbiology, Arsanjan Branch, Islamic Azad University, Arsanjan, Iran
2 - Department of Microbiology, Jahrom Branch, Islamic Azad University, Jahrom, Iran
3 - Department of Microbiology, Jahrom Branch, Islamic Azad University, Jahrom, Iran
4 - Department of Microbiology, Marvdasht Branch, Young Researcher's Club, Islamic Azad University, Marvdasht, Iran
5 - Department of Microbiology, Science and Researches Branch, Islamic Azad University, Fars, Iran
6 - Department of Microbiology, Jahrom Branch, Young Researcher's Club, Islamic Azad University, Jahrom, Iran

Received: 2010-04-14 Accepted : 2010-05-15 Published : 2010-04-01

Keywords: Multiplex PCR, E. coli O157:H7, Virulence genes,

Abstract :

Background and Objective: Shiga Toxin-Producing Escherichia coli (STEC) strains can infect humans via vegetal and animal food consumption and cause food poisoning with diarrhoeas, hemorrhagic colitis, haemolytic uraemic syndrome that can lead to death. The purpose of this study is isolation and identification of Escherichia coli O157:H7 virulence genes from Juice Purchase and vegetables in Shiraz. Material and Methods: This cross- sectional study was performed on 89 samples of Juice Purchase and vegetables collected from Shiraz. Isolates were enriched in ECB with novobiocin medium in temperature37°C. After, in order to examine the fermentation of sorbitol and lactose the CT-SMAC and VRBA media and the activities of β-glucoronidase of separated bacteria were examined using the choromoagar medium. Then, the existence of E.coli O157:H7 was confirmed with the spesific antiserum. Finally, virulence genes stx1, stx2, eae and hly were tested by multiplex PCR and rfb O157 and fliC H7 were tested by single PCR. Results: Out of all examined samples 69 (77.53%) sorbitol negative bacteria were separated that after evaluation with specific antiserum 21 (23.60%) E.coli O157:H7 was detected. The molecular markers, stx1 genes in 3 samples and eae , stx1 in 1 sample were detected. Conclusion: Intensive studies of the sources, incidence, fate and transport of E.coli O157 near produce production are required to determine the mechanisms of pre-harvest contamination and potential risks for human.

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