Spread of Clonally Related Escherichia coli Strains Harboring an IncA/C(1) Plasmid Encoding IMP-8 and Its Recruitment into an Unrelated MCR-1-Containing Isolate

Ten IMP-8-producing Escherichia coli isolates were recovered from surveillance cultures of a neonatal intensive care unit; eight of the isolates were clonally related. A 168.2-kb bla(IMP-8) plasmid was fully sequenced, and it corresponded to the recently described IncA/C1-ST13 plasmid. This plasmid was detected in all isolates, even in those that were not clonally related. One unrelated isolate was also resistant to colistin and positive for mcr-1 This marker was located in a 62.7-kb IncI2 plasmid, which was also fully sequenced.