Molecular Characterization of Shiga Toxin-producing Escherichia coli Isolated from Some Food Products as well as Human Stool in Alexandria, Egypt

The goal of the current investigation was to test various samples of ready-to-eat food and human stool for EPEC. A total of 450 food product samples, including chicken paneeh, chicken burgers, chicken luncheons, beef burgers, minced meat, and kariesh cheese (75 each), and 100 human stool samples (60 from diarrheal people and 40 from healthy people) were randomly gathered from various supermarkets in the Alexandria province. To isolate and identify enteropathogenic E. coli, samples were examined bacteriologically. In addition, the recovered isolates underwent a molecular approach employing PCR assay for the simultaneous detection of four virulence indicators, and the antibiogram pattern of the isolates was established. It was found that the highest rate of isolation of E. coli was recorded in the examined samples of chicken paneeh (8%) followed by chicken luncheon and minced meat (5.3% of each), Kariesh cheese (4%) and lastly beef burger (2.7%). Concerning stool samples, the rate of isolation was 11.7% and 5% in diarrheic and apparently healthy individuals, respectively. Serotyping of the recovered E. coli isolates (n=21) from food samples revealed the detection of serotype O157:𝐻7 (EHEC) (47.6%), serotype O111:H8 (EHEC) (23.8 %), serotype O26:H11 (EHEC) (19.0%), serotype O125:H21 (ETEC) (4.8%) and serotype O128:H2 (EAEC) (4.8%) while identified serotypes from stool samples (n=9) were O127:𝐻40 serotype (EPEC) (33.3 %), O115:H83 serotype (EPEC) (55.56 % ) and O157:H7 serotype (EHEC) (11.1%). Antimicrobial susceptibility of E. coli strains to 11 antimicrobial agents was performed. The recorded results clarified that STEC isolated was found to be highly sensitive to Nalidixic acid (76.19%, 77.7%) and Doxycycline (90.5%, 88.89%), while it was moderately sensitive to Ampicillin (52.3%, 44.4%) and Erythromycin (47.6 %, 44.4%). Moreover, it was high resistance to Vancomycin (76.19%, 77.7 %) and cephalexin (81.0%, 77.7%) from food and stool respectively. The recovered E. coli isolates from the tested materials, either chicken products or stool, were effectively molecularly characterized using Real time PCR, which included the Stx1, Stx2, eaeA, and hylA genes. Despite the relatively low rate of isolation of enteropathogenic E. coli, it was determined from the data that retail food products in Alexandria pose a risk to human health.