Emergence of IS26-mediated pLVPK-like virulence and NDM-1 conjugative fusion plasmid in hypervirulent carbapenem-resistant Klebsiella pneumoniae

Hypervirulent carbapenem-resistant Klebsiella pneumoniae (hv-CRKP) has been widely reported and poses a global threat. However, the comprehensive genetic structure of ST11-KL64 hv-CRKP and the possible evolutionary mechanisms from a genetic structure perspective of this high-risk clone remain unclear. Here, a blaKPC-2blaNDM-1-positive ST11-KL64 hv-CRKP isolate was obtained from a human bloodstream infection (BSI). Wholegenome sequencing and bioinformatics analyses revealed that it contained a fusion plasmid, pKPTCM2-1. pKPTCM2-1 is a conjugative plasmid composed of an oriT-positive pLVPK-like virulence plasmid and a type IV secretion system-produced blaNDM-1-bearing IncX3 plasmid mediated by IS26-based co-integration. This progress generated 8-bp target site duplications (TGAAAACC) on both sides. The fusion plasmid possessed selftransferability and could be transferred to bla(KPC-2)-harboring ST11-KL64 CRKP to form the ST11-KL64 hvCRKP clone. The pLVPK-like-positive ST11-KL64 strain exhibited virulence levels similar to those of the typical hypervirulent K. pneumoniae NTUH-2044. The mutation, Tet(A) (A276S), which was believed to lead to tigecycline resistance was observed. Overall, this high-risk clone has emerged as a tremendous threat in fatal BSIs and thus, targeted surveillance is an urgent need to contain the hv-CRKP clones.