The Antimicrobial Susceptibility and Detection of Virulence Genes of Escherichia coli O157:H7 Isolated from Leafy Green Vegetables

Abstract

Vegetables can be vehicles for transmission of E. coli O157:H7 to humans, therefore, this study carried out in order to investigate the presence of Enterohemorrhagic E. coli in ten different types of leafy green vegetables, determined their susceptibility to thirteen antibiotics and detected the presence of some virulence genes.
 Method: Five-hundred samples of green leafy vegetables namely (Lettuce, Spanish, Rocket, Parsley, Mallow, Coriander, Portulaca, Lettuce, Dill, Basil and Chard) were examined for presence of E. coli O157:H7, by using standard microbiological tests (CHROMagarTM O157:H7), further detection of E. coli O157:H7 was done by Multiplex PCR (mPCR) for the detection of virulence genes (stx1, stx2, intmin and hlyA) These genes are causative factors of settlement, adhesion, and attack of STEC bacteria to gastrointestinal mucosa.
 Results: E. coli O157:H7 was isolated from eight (80%) out of ten types of green leafy vegetable as 12 (2.40%) in which the highest percentage of isolation was shown in Dill and Chards samples as (4.2%), Coriander and Mallow showed percentage of isolation as (3.33% and 3.03%) respectively, Parsley, Portulaca and Lettuce showed percentages of isolation as 2.43%, 1.92%, respectively, the least percentage of isolation was shown in Rocket (1.7%), No E. coli O157:H7, was detected in Spinach and Basil. Makkah collected samples showed isolation of 7 isolates out of 12 (58.33%). All isolates were resistant to Methicillin (5µg), Metronidazole (5 µg) and Ampicillin (10 µg). Stx2 (110 bp), Stx1 (349 bp), hly A (165 bp) genes were detected. All isolates showed negative results for presence of intimin gene (890 bp). This study concluded that there is a high risk for occurrence of E. coli O157:H7 outbreaks due to consumption of the green leafy vegetables sold in Jeddah Central Market.