A novel plasmid-mediated IMI-1-like carbapenemase
Objective To investigate the resistant mechanism of imipenem-resistant Enterobacter cloacae. Methods The minimal inhibitive concentration (MIC) was detected by E test. Isoelectric focusing electrophoresis(IEF), three dimensional test, conjugation experiment, Southern blot, polymerase chain reaction(PCR), cloning and sequencing methods were applied for analyzing the enzyme activity and the encoding gene. Results The carbapenemase produced by Enterobacter cloacae had the bands with pIs 8.1. The carbapenemase had some characteristics of Class 2f. The activity of hydrolysising imipenem was inhibited by clavulanic acid, but not inhibited by cloxacillion and EDTA. The imipemen-resistant gene was located on a about 80kb plasmid and the amino acid sequence have 99% of homology with chromosome-mediated IMI-1. Conclusion The E. cloacae resistant to imipenem was explained by a novel plasmid-mediated IMI-1-like carbapenemase.