We describe the first report of a clinical colistin-resistant ST84 Enterobacter cloacae isolate coharboring mcr-4.3 (previously named mcr-4.2) and blaNDM-1 from a patient in China. The blaNDM-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.
Keywords: NDM-1; carbapenem resistant; colistin; mcr-4; plasmid.
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