Co-occurrence of clinically relevant β-lactamases and MCR-1 encoding genes in Escherichia coli from companion animals in Argentina.

•Resistance to cephalosporins and colistin in E. coli infections in pet has been investigated.•Occurrence of CMY-2 and CTX-M-type β-lactamases is reported.•Identification of MCR-1 and CTX-M-2 co-producing E. coli ST770 in a dog infection is highlighted.•Genomic analysis revealed that mcr-1 gene was carried by a ˜60-kb IncI2 plasmid.•Dissemination of MDR E. coli in companion animals, in Argentina, has been discussed.