Mobilization of the bla(KPC-14) gene among heterogenous plasmids in extensively drug-resistant hypervirulent Klebsiella pneumoniae

INTRODUCTION: Ceftazidime/avibactam (CZA) is an effective alternative for the treatment of infections caused by KPC-producing carbapenem-resistant Klebsiella pneumoniae (CRKP). However, KPC variants with CZA resistance have been observed in clinical isolates, further limiting the treatment options of clinical use. METHODS: In this study, we isolated three KPC-14-producing CRKP from two patients in intensive care units without CZA therapy. The antimicrobial susceptibility was determined using the broth microdilution method. Three CRKP were subjected to whole-genome sequencing to analyze the phylogenetic relatedness and the carriage of antimicrobial resistance genes and virulence factors. Long-read sequencing was also performed to obtain the complete sequences of the plasmids. The horizontal transfer of the bla(KPC-14) gene was evaluated by conjugation experiments. RESULTS: Three CRKP displayed resistance or reduced susceptibility to ceftazidime/avibactam, colistin, and tigecycline. Single-nucleotide polymorphism (SNP) analysis demonstrated the close phylogenetic distance between these strains. A highly similar IncFII/IncR plasmid encoding bla(KPC-14) was shared by three CRKP, with bla(KPC-14) located in an NTE(KPC)-Ib element with the core region of ISKpn27- bla(KPC-14)-ISKpn6. This structure containing bla(KPC-14) was also observed in another tet(A)-carrying plasmid that belonged to an unknown Inc-type in two out of three isolates. The horizontal transferability of these integrated plasmids to Escherichia coli EC600 was confirmed by the cotransmission of tet(A) and bla(KPC-14) genes, but the single transfer of bla(KPC-14) on the IncFII/IncR plasmid failed. Three CRKP expressed yersiniabactin and carried a hypervirulence plasmid encoding rmpA2 and aerobactin-related genes, and were thus classified as carbapenem-resistant hypervirulent K. pneumoniae (hvKP). DISCUSSION: In this study, we reported the evolution of a mosaic plasmid encoding the bla(KPC-14) gene via mobile elements in extensively drug-resistant hvKP. The bla(KPC-14) gene is prone to integrate into other conjugative plasmids via the NTE(KPC)-Ib element, further facilitating the spread of ceftazidime/avibactam resistance.