Co-transfer of bla and mcr-1 by an IncX3-X4 hybrid plasmid in Escherichia coli.

Carbapenem and colistin are the last-resort antibiotics used for treating multidrug-resistant Gram-negative pathogens. Here, we report, for the first time, co-transfer of resistance to both classes of antibiotics by a mobile IncX3-X4 hybrid plasmid in an Escherichia coli isolate. Spread of such a plasmid is of great concern for clinical therapy, and heightened efforts are needed to control its dissemination.

Emergence of NDM-5- and MCR-1-Producing Escherichia coli Clones ST648 and ST156 from a Single Muscovy Duck (Cairina moschata).

Two Escherichia coli clones (sequence type 648 [ST648] and ST156) that coproduce NDM-5 and MCR-1 were detected from a single fowl in China. The bla gene was found on the two indistinguishable IncX3 plasmids from the two different E. coli isolates, whereas the mcr-1 gene was located on IncHI2 and IncI2 plasmids, respectively, suggesting that bla and mcr-1 have spread in avian intestinal flora.