Occurrence, Molecular Detection and Antibiotic Resistance Profile of Escherichia coli O157:H7 Isolated from Ready-to-Eat Vegetable Salads in Iran

Background: Escherichia coli O157:H7 is one of the high risk bacteria, found in foods, especially in ready-to-eat products, which causes many disorders such as hemorrhagic colitis, hemolytic uremic syndrome and dysentery in humans. The objective of this study was to determine the contamination of Escherichia coli O157:H7 and antibiotic resistance in ready-to-eat vegetable salads. Methods: In this study, 6o ready-to-eat salad vegetable samples were collected from restaurants for determining their isolated Escherichia coli O157:H7 and their antibiotic resistance by SYBR Green I Based real-time PCR and disc diffusion method, respectively. Results: Out of the 60 samples, 10 samples (16.66%) were positive for Escherichia coli O157:H7. All identified isolates were resistant to more than five antibiotics. A high rate of resistance was observed to the clindamycin, vancomycin, erythromycin, penicillin, amoxicillin and cephalothin (100%), cefixime (40%), amikacin (20%), cefotaxime and cetracycline (10%). Conclusion: The presence of toxigenic Escherichia coli O157:H7 in ready-to-eat vegetable salads can be considered a public health threat. Providing the useful strategies for improving food safety and inspection services is necessary. Further studies are suggested to identify specific ready-to-eat vegetable salads-related hazards.