Emergence of Carbapenem-Resistant Hypervirulent ST111 K63 Klebsiella pneumoniae in China

Carbapenem-resistant and hypervirulent Klebsiella pneumoniae have been identified worldwide, posing a significant threat to public health. This study aimed to characterize a novel KPC-harboring plasmid in a carbapenem-resistant and hypervirulent ST111 K63 Klebsiella pneumoniae (CR-HvKp), designated AZJ065, and to analyze the evolutionary pathway of multidrug-resistant and hypervirulent clinical ST111 K63 strains using genomic data. Antimicrobial susceptibility testing, the string test, the Galleria mellonella infection model, and the mouse intraperitoneal challenge infection model were employed to determine the drug resistance and virulence of the clinical strains. Next-generation sequencing and phylogenetic analysis were conducted to investigate the genetic characteristics of AZJ065 and the evolutionary pathway of ST111 K63. Phenotypic tests indicated that AZJ065 exhibited carbapenem resistance and hypervirulence. Next-generation sequencing analysis revealed that AZJ065 harbored two plasmids: a KPC-harboring plasmid, pAZJ065-KPC, and a virulence plasmid, pAZJ065-Hv. The pAZJ065-KPC conferred carbapenem resistance and displayed a unique structure in the resistance region, with a complete Tn2680 insertion. Phylogenetic analysis suggested that AZJ065 evolved from an ST111 K63 HvKp through the acquisition of a CR plasmid. This study reports a new genotype of HvKp, ST111 K63, and highlights the importance of monitoring plasmid-mediated resistance in hypervirulent strains.