Coexistence of blaIMP-4, blaNDM-1 and blaOXA-1 in blaKPC-2-producing Citrobacter freundii of clinical origin in China

Abstract

We found <i>C. freundii</i> carrying <i>bla</i>_IMP-4, <i>bla</i>_NDM-1, <i>bla</i>_OXA-1, and <i>bla</i>_KPC-2 for the first time, and conducted in-depth research on its drug resistance mechanism, molecular transfer mechanism and epidemiology. In particular, we found that <i>bla</i>_IMP-4, <i>bla</i>_OXA-1, and <i>bla</i>_NDM-1 coexisted on a new transferable hybrid plasmid that carried many drug resistance genes and insertion sequences. The plasmid may capture more resistance genes, raising our concern about the emergence of new resistance strains.