Plasmid-mediated carbapenem-hydrolyzing enzyme KPC-2 and ArmA 16S rRNA methylase conferring high-level aminoglycoside resistance in carbapenem-resistant Enterobacter cloacae in China

The emergence and spread of carbapenem-resistant Enterobacteriaceae in the world are a major concern. We investigated 5 isolates of Enterobacter cloacae that were resistant to all clinically available antimicrobial agents, except polymyxin B. The MICs of imipenem and aminoglycosides were >32 and >256 mg/L, respectively. All of the isolates produced 5 extended-spectrum beta-lactamase (ESBLs) with pIs of 5.4 (TEM-1), 6.7 (KPC-2), 8.2 (SHV-12), 8.4 (CTX-M-14), and ArmA 16S rRNA methylase. blaKPC-2 was located on a large nonconjugative plasmid, whereas armA was located on another conjugative plasmid. Although carbapenem-resistant Enterobacteriaceae remains rare, the emergence of this group of organism merits monitoring.