Abstract
The rapidly increasing prevalence of Klebsiella pneumoniae carbapenemase 2 (KPC-2)-producing bacteria has become a serious challenge to public health. Currently, the bla (KPC-) (2) gene is mainly disseminated through plasmids of different sizes and replicon types. However, the plasmids carrying the bla (KPC-) (2) gene have not been fully characterized. In this study, we report the complete genome sequences of two novel bla (KPC-) (2)-harboring incompatibility group U (IncU) plasmids, pEC2341-KPC and pEC2547-KPC, from international high-risk clones of Escherichia coli isolated from Zhejiang, China. Two KPC-2-producing E. coli isolates (EC2341 and EC2547) were collected from clinical samples. Whole-genome sequencing (WGS) analysis indicated that EC2341 and EC2547 belonged to the ST410 and ST131 clones, respectively. S1-nuclease pulsed-field gel electrophoresis (S1-PFGE), Southern blot and conjugation experiments confirmed the presence of the bla (KPC-) (2) gene on the pEC2341-KPC plasmid and that this was a conjugative plasmid, while the bla (KPC-) (2) gene on the pEC2547-KPC plasmid was a non-conjugative plasmid. In addition, plasmid analysis further revealed that the two bla (KPC-) (2)-harboring plasmids have a close evolutionary relationship. To the best of our knowledge, this is the first report of E. coli strains carrying the bla (KPC-) (2) gene on IncU plasmids. The emergence of the IncU-type bla (KPC-) (2)-positive plasmid highlights further dissemination of bla (KPC-) (2) in Enterobacteriaceae. Therefore, effective measures should be taken immediately to prevent the spread of these bla (KPC-) (2) (-)positive plasmids.