Study of the Contamination Rate of Vegetables by Enterohemorrhagic Escherichia coli (EHEC) Using Multiplex PCR and Cultivation Methods in Ahvaz Province

Enterohemorrhagic Escherichia coli is a pathogen that can be transmitted to humans through food products and causes dangerous diseases such as hemorrhagic colitis and hemolytic uremic syndrome in humans because of shiga toxin production.
In this research, 256 samples of fresh vegetables including lettuce, cabbage and eating herbs were prepared from 4 vegetable wholesale centers in the city of Ahvaz during 8 months. After primary enrichment, Sorbitol negative colonies grown on CT-SMAC medium were subcultured on differential culture media and confirmed as E. coli by specific biochemical tests. Confirmed strains were then investigated by E.coli O157:H7 antiserum. Finally, the presence of stx2, stx1, eaeA and hlyA genes was evaluated in sorbitol negative strains using multiplex PCR.
8 E.coli O157 (3.1%) bacteria were detected, only 2 isolates were identified as E.coli O157:H7. After multiplex PCR it became clear that 4 isolates contained stx1 gene, 2 isolates stx2 gene, 1 isolate stx1 and eaeA genes, 1 isolate stx1, eaeA and hlyA genes and 1 isolate stx1 and hlyA genes. None of the isolates contained all four genes.
The presence of E.coli bacteria in vegetables is problematic for public health and can cause food-borne diseases.