| Objective: To study resistance mechanism and molecular epidemiological characteristics of carbapenem resistant Enterobacter cloacae.To provide scientific basis for rational use of antimicrobial drugs in clinic and for reducing hospital infection rate.Methods: Four strains of Enterobacter cloacae resistant to carbapenem were collected from March 2016 to December 2016 in The Second Affiliated Hospital of Nanchang University.MICs of 16 antimicrobial agents were tested by VITEK MS and VITEK2 compact;Carbapenem enzyme was detected by the modified Hodge test and modified Carbapenem Inactivation Method(mCIM).Resistant genes such as extended spectrum betalactamases(ESBLs),Ampc,carbapenemases and quinolones were amplified and sequenced by PCR.Homology analysis was performed by pulsed-field gel electrophoresis(PFGE),and the plasmid characteristics were analyzed by conjugation experiments and S1-PFGE.Results: The three strains were resistant to cephalosporins,carbapentic and quinolones,and the other isolate was only resistant to cephalosporins and carbapenems.All strains were positive by the modified Hodge test and mCIM method.Among them,blaNDM-1 was detected in 2 strains,blaNDM-5 was detected in 1 strain,blaIMP-4 was detected in 1 strain.Meanwhile,only one strain was detected the extended spectrum β-lactamase gene TEM-135.PFGE results 4 PFGE-DNA patterns for all strains.Three strains of Enterobacter cloacae were positive by conjugation test and obtain similar resistance to competent cell.S1-PFGE showed four strains of Enterobacter cloacae with different size plasmids.Conclusion: blaNDM which is the main mechanism for Enterobacter cloacae with resistance carbapenem and mainly located on transferable plasmids.For the first time,blaNDM-5 gene was found in Enterobacter cloacae and clonal spread was not observed.The 4 strains were all multidrug-resistant strains,and all were high-level resistant to carbon penicilene antimicrobial drugs.Amikacin resistant strain was not found. |
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