Colistin- and cefotaxime-resistant Shiga toxin-producing Escherichia coli (STEC) in buffalo meat

In this study, Shiga toxin-producing E. coli (STEC) were detected in 64% of all tested buffalo meat samples, distributed as 62% of buffalo meat chops and 66% of ground buffalo meat. Six serotypes (O55:H7, O111:H8, O145, O157:H7, O26:H11, and O103:H2) were identified, of which, O55:H7 (37.26%) and O111:H8 (21.29%) were the most predominant. The eaeA, stx1, stx2, and EHEC-hlyA were detected by multiplex PCR in all E. coli isolates at different percentages, and multiple virulence patterns with stx2/stx1/eae were the most prevalent pattern indicating that the serotypes will be more virulent in pathogenesis. The isolates showed high resistance rates against Erythromycin (100%), Clindamycin (86.7%), Nalidixic acid (84.4%), Cefepime (73.4%), and Ampicillin (62.7%), Cefazolin (53.2%) and Tetracycline (51.7%) and most of the isolates (73%) were classified as multi-drug resistant (MDR). For the first time, we identified a high frequency of Cefotaxime-resistant (28.5%) and Colistin-resistant (16.3%) E. coli from buffalo meat and this becomes a huge problem because Cefotaxime and colistin are typically used as a last resort to treat complex infections caused by multidrug-resistant Gram-negative bacilli. The emergence of virulent and multidrug-resistant E. coli strains in food seriously threatens human health. This highlights the need for antimicrobial stewardship programs in developing countries like Egypt to minimize the spread and emergence of these strains and prevent their dissemination to humans.