Coidentification of <i>mcr-4.3</i> and <i>bla</i> _NDM-1 in a Clinical Enterobacter cloacae Isolate from China

Abstract

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