Lab Med Online.  2018 Jul;8(3):99-106. 10.3343/lmo.2018.8.3.99.

Biological and Genetic Characteristics of Clinically Isolated Enterobacter cloacae with Multidrug Resistance

  • 1Department of Laboratory Medicine, St. Mary's Hospital, Daejeon Catholic University, Daejeon, Korea.
  • 2Department of Laboratory Medicine, Chungnam National University Hospital, Daejeon, Korea.


From January 2014 to December 2015, 69 clones of Enterobacter cloacae showing multidrug resistance to six classes of antimicrobial agents were collected from two medical centers in Korea.
Minimum inhibitory concentrations were determined using the E-test method, and 17 genes were detected using polymerase chain reaction (PCR). The epidemiological relatedness of the strains was identified using repetitive element sequence-based PCR and multilocus sequence typing.
The 69 E. cloacae clones produced extended spectrum β lactamase (ESBL) and AmpC and showed multidrug resistance to cefotaxime, ceftazidime, and aztreonam. We identified the following sequence types: ST56 of type VI for ESBL SHV (N=12, 17.4%); ST53, ST114, ST113, and ST550 of types I, IV, VI, and VII, respectively, for CTX-M (N=11, 15.9%); and ST668 of type III for the carbapenemase NDM gene (N=1, 1.5%). The AmpC DHA gene (N=2, 2.89%) was confirmed as ST134, although its type was not identified, whereas EBC (MIR/ACT; N=18, 26.1%) was identified as ST53, ST24, ST41, ST114, ST442, ST446, ST484, and ST550 of types V, I, III, IV, VII, and VI, respectively. The formed subclasses were bla CTX-M-3 and bla CTX-M-22 by CTX-M-1, bla CTX-M-9 and bla CTX-M-125 by CTX-M-9, bla DHA-1 by DHA, and bla MIR-7 and bla ACT-15,17,18,25,27,28 by EBC (MIR/ACT).
There were no epidemiological relationships between the gene products and the occurrence of resistance among the strains.


Enterobacter cloacae; Extended spectrum β lactamase; AmpC; Repetitive element sequence-based polymerase chain reaction; Multilocus sequence typing; Multidrug resistance
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