Prevalence of colistin-resistant Escherichia coli harbouring mcr-1 in raw beef and ready-to-eat beef products in Egypt

Abstract

The emergence of antibiotic-resistant bacteria in food, mainly contaminated meat and its products, and their transfer to humans is of great concern. To evaluate the potential risk of such contamination in Egypt, we isolated Escherichia coli from 78% (51/65) of raw beef and 53% (24/45) of ready-to-eat beef products. Of the 210 E. coli isolates detected, 8 (3.8%) harboured mcr-1 gene and were resistant to colistin, whereas 5 (2.4%) were positive for the blaCTX-M-28 gene and were resistant to cefotaxime. Among the colistin-resistant isolates, three had both mcr-1 and extended-spectrum beta-lactamase (ESBL) genes, constituting a great public health concern. The sequence types of all these mcr and/or ESBL-positive isolates were variable, suggesting that colistin and/or cephalosporin resistance spread through the mediation of plasmids harbouring mcr-1 or ESBL genes in Egyptian beef. In addition, various extraintestinal virulence genes were observed in some isolates. Colistin and cephalosporins are frequently used for livestock in Egypt; hence the present results suggest colistin and cephalosporin-resistant pathogenic E. coli are transferred from food animals to humans via meat and meat-derived products. Therefore, the rational use of antimicrobials and the appropriate safety measures in food production are needed in Egypt as well as in other developing countries.