Abstract
We describe the first report of a clinical colistin-resistant ST84 Enterobacter cloacae isolate coharboring mcr-4.3 (previously named mcr-4.2) and bla(NDM-1) from a patient in China. The bla(NDM-1)-harboring IncX3 plasmid and the novel mcr-4.3-harboring ColE plasmid were completely sequenced. Although this isolate showed a high level of resistance to colistin, mcr-4.3 plasmid transformation, gene subcloning, susceptibility testing, and lipid A matrix-assisted laser desorption ionization mass spectrometry analysis indicated that mcr-4.3 itself does not confer resistance to colistin.