LAUSR

OBJECTIVES Multidrug-resistant bacteria have become a serious threat worldwide. In particular, the coexistence of carbapenemase genes and mcr-1 leaves few available treatment options. Here we report a multidrug-resistant Escherichia coli isolate harbouring both mcr-1 and blaNDM-9 from a patient with a urinary tract infection. METHODS Antimicrobial susceptibility and resistance genes of the E. coli isolate were characterised. Furthermore, the assembled genome sequences of mcr-1- and blaNDM-9-carrying plasmids were determined and comparative genetic analysis with closely related plasmids was carried out. RESULTS Three contigs were assembled comprising the E. coli chromosome and two plasmids harbouring mcr-1 (p5CRE51-MCR-1) and blaNDM-9 (p5CRE51-NDM-9), respectively. Whole-genome sequencing revealed that the two antimicrobial resistance genes are located on individual plasmids. CONCLUSIONS The emergence of coexistence of carbapenemase genes and mcr-1 in Enterobacteriaceae highlights a serious threat to antimicrobial therapy.