Detection of KPC-2 in a Clinical Isolate of Proteus mirabilis and First Reported Description of Carbapenemase Resistance Caused by a KPC β-Lactamase in P. mirabilis

An isolate of Proteus mirabilis recovered from blood cultures of a diabetic patient was shown to be resistant to imipenem, meropenem, and ertapenem by disk diffusion susceptibility testing. Amplification of whole-cell and/or plasmid DNA recovered from the isolate with primers specific for the bla(KPC) carbapenemase gene produced an amplicon of the expected size which was confirmed to be bla(KPC-2) by sequence analysis. Transformation of a susceptible Escherichia coli host with plasmid preparations from the isolate generated a transformant for which the MICs of all of the carbapenems tested were increased three- to fourfold. We believe this to be the first report of carbapenem resistance in P. mirabilis caused by the acquisition of bla(KPC).