Comparative analysis of - and -carrying IncFII-family pKPC-LK30/pHN7A8 hybrid plasmids from CG258 strains disseminated among multiple Chinese hospitals.

Background: We recently reported the complete sequence of a KPC-2- and -carrying IncFII-family plasmid p675920-1 with the pKPC-LK30/pHN7A8 hybrid structure. Comparative genomics of additional sequenced plasmids with similar hybrid structures and their prevalence in -carrying strains from China were investigated in this follow-up study.

Methods: A total of 51 -carrying strains were isolated from 2012 to 2016 from five Chinese hospitals and genotyped by multilocus sequence typing. The -carrying plasmids from four representative strains were sequenced and compared with p675920-1 and pCT-KPC. Plasmid transfer, carbapenemase activity determination, and bacterial antimicrobial susceptibility test were performed to characterize resistance phenotypes mediated by these plasmids. The prevalence of pCT-KPC-like plasmids in these -carrying strains was screened by PCR.

Result: The six KPC-encoding plasmids p1068-KPC, p20049-KPC, p12139-KPC and p64917-KPC (sequenced in this study) and p675920-1 and pCT-KPC slightly differed from one another due to deletion and acquisition of various backbone and accessory regions. Two major accessory resistance regions, which included the KPC-2 region harboring KPC-2 (carbapenem resistance) and SHV-12 (β-lactam resistance), and the MDR region carrying (aminoglycoside resistance), (fosfomycin resistance), (β-lactam resistance) and (β-lactam resistance), were found in each of these six plasmids and exhibited several parallel evolution routes. The pCT-KPC-like plasmids were present in all the 51 isolates, all of which belonged to CG258.

Conclusion: There was clonal dissemination of CG258 strains, harboring - and -carrying IncFII-family pKPC-LK30/pHN7A8 hybrid plasmids, among multiple Chinese hospitals.