Emergence of an Escherichia coli strain co-harbouring mcr-1 and blaNDM-9 from a urinary tract infection in Taiwan

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 bla(NDM-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 bla(NDM-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 bla(NDM-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. (C) 2018 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.