Genomic characterization of IMP and VIM carbapenemase-encoding transferable plasmids of Enterobacteriaceae

IMP and VIM carbapenemases, in association with class 1 integrons, have spread globally among multiple Enterobacteriaceae species. We characterized IMP- and VIM-encoding transferable plasmids of clinical Enterobacteriaceae collected from two global surveillance programmes.

We performed conjugation and transformation experiments for 38 IMP and 89 VIM producers. Plasmids, obtained from transconjugants or transformants, were sequenced with Illumina next-generation sequencing and analysed for replicon types and antimicrobial resistance genes.

A total of 41 transconjugants (blaIMP, n = 22; blaVIM, n = 19) and 10 transformants (blaIMP, n = 1; blaVIM, n = 9) were obtained. Broad-host-range IncL/M, IncC and IncN plasmids were associated with blaIMP and blaVIM, contained various integrons and showed inter-species and international distribution. Narrow-host-range IncFII(K) plasmids were limited to Klebsiella pneumoniae with blaIMP-26 from the Philippines, while IncR and IncHI1B-IncFIB(Mar) plasmids were restricted to K. pneumoniae with blaVIM from Greece and Spain. IncA-like hybrid plasmids were detected in Enterobacter xiangfangensis from Italy and K. pneumoniae from Spain. Transferable plasmids were major contributors of antimicrobial resistance genes among Enterobacteriaceae with blaIMP and blaVIM.

This is the first report, to the best of our knowledge, describing blaIMP on IncFII(K) plasmids and blaVIM on IncL/M, IncN2, IncHI1B-IncFIB(Mar) and IncX3-IncC-like plasmids and showed that broad-host-range and narrow-host-range plasmids have contributed to the global spread of blaIMP and blaVIM among different species. This study highlights the importance of molecular analysis of plasmids in providing insight into horizontal spread of these carbapenemases.