Characterization of pKPN945B, a novel transferable IncR plasmid from hypervirulent carbapenem-resistant <i>Klebsiella pneumoniae</i> , harboring <i>bla</i> _IMP-4 and <i>qnrS1</i>

Up to now, IncR replicons carrying <i>bla</i>_IMP-4 have not been reported, and the IncR plasmids described in previous studies have been found to be non-transferrable to other bacteria through conjugation. Moreover, there have been no extensive phylogenetic analyses of strains carrying blaIMP in the published papers. The lack of data in these studies is noteworthy because blaIMP appears in the novel transferable fusion plasmid IncR. Although the IncR plasmid has no tra operon, it can still be transferred to <i>Escherichia coli</i> EC600 or <i>Klebsiella</i> pneumoniae ATCC13883 (RIF^R) without high fitness cost, but it only affects the MIC of imipenem. <i>bla</i>_IMP integrates with other resistance mechanisms leading to the formation of multidrug-resistant strains. Notably, the high prevalence of <i>bla</i>_IMP-4 in Asia and the presence of <i>bla</i>_IMP-4 on novel transferable IncR plasmids suggest the urgent need to monitor the emergence of such plasmids and control their spread.