Abstract

Escherichia coli strains that produce Shiga toxin (STEC) represent a significant cause of foodborne disease, associated with serious clinical outcomes in humans. This study assessed the prevalence, serogroup distribution, resistance to antimicrobial drugs, and virulence factors of STEC in ready-to-eat (RTE) meat products and human fecal sources. The study analysed 200 samples (150 RTE meat products involving burger, kofta, sausage - and 50 human stool samples) for STEC contamination through standard microbiological techniques and serogroup typing. Antimicrobial resistance profiles were determined via disc diffusion assay, while PCR was employed to identify resistance and virulence determinants. STEC was recovered from 33 samples (16.5%), with a percentage of 12 in RTE meat and 30% in stool specimens. Among the 33 isolates, 13 different serogroups were identified. O157 was the most common (27.2%), followed by non-O157 serogroups such as O128, O91, and O55. All recovered isolates showed resistance to penicillin and amoxicillin. High resistance ratios were noted for amoxicillin-clavulanic acid (81.8%), cefotaxime (75.7%) and tetracyclines (66.7%). We report a high multidrug-resistant prevalence (69.7%) and the alarming emergence of pandrug-resistant and extensively drug-resistant O157:H7 in human patients, highlighting a serious public health concern. Three resistance genes (blaOXA, blaTEM, blaCTX-M1) and four virulence genes (stx1, stx2, eaeA, hlyA) were found. The stx1 gene was the most prevalent (33.3%), while stx2, eaeA, and hlyA were demonstrated in fewer isolates. The study highlights a notable occurrence of STEC, including O157 and non-O157 serogroups, in both food and clinical samples. The high rate of multidrug resistance and presence of virulence genes underscore the public health risk associated with contaminated RTE meat and the need for ongoing surveillance and improved food safety practices.

Key words: Shiga toxin Escherichia coli, Ready to-Eat Meat, Antibiotic resistance, Virulence genes, Multidrug-resistant