Emergence of Proteus mirabilis Harboring bla KPC-2 and qnrD in a Chinese Hospital

Nineteen carbapenem-nonsusceptibleProteus mirabilis isolates were recovered from intensive care units in the Second Affiliated Hospital of Zhejiang University during a 3-month period. The isolates showed a high level of resistance against ciprofloxacin, in addition to their resistance against the carbapenems. Pulsed-field gel electrophoresis (PFGE) analysis showed that these isolates belonged to three clonal strains. PCRs and DNA sequence analysis of the carbapenemase and other β-lactamase genes indicated that all the isolates harbored thebla KPC-2 gene. Twelve of 19 isolates harbored the plasmid-mediated quinolone resistance (PMQR) genes, both theqnrD andaac(6 ′)-Ib-cr genes. Eight representative isolates with high levels of quinolone resistance carried the similar mutation profiles of S83I ingyrA , E466D ingyrB , and S80I inparC . Reduced carbapenem susceptibility was transferred toEscherichia coli (EC600) in a conjugation experiment, while the quinolone resistance was not. DNA hybridization showed thatqnrD was located on a plasmid of approximately 4.5 kb. In summary, large clonally related isolates of KPC-2-producingP. mirabilis emerged in a Chinese hospital, andqnrD was detected in KPC-producingP. mirabilis for the first time.