Dissemination of <i>bla</i> _NDM -harboring plasmids in carbapenem-resistant and hypervirulent <i>Klebsiella pneumoniae</i>

Carbapenem-resistant <i>Klebsiella pneumoniae</i> (CRKP) is a global public health threat, and CRKP strains carrying <i>bla</i>_NDM plasmids are of particular concern. Here, the antimicrobial resistance and molecular epidemiological characteristics of 59 CRKP strains isolated from patients receiving care at a tertiary hospital in China from 2019 to 2021 were determined through antimicrobial resistance testing and genomic sequence analysis. We analyzed the genetic characteristics and transmissibility of <i>bla</i>_NDM-harboring plasmids through S1-digested pulsed field gel electrophoresis, Southern blotting, and conjugation assays. The virulence levels of the strains were evaluated using a <i>Galleria mellonella</i> larvae infection model. All the CRKP strains were multidrug resistant, but none were resistant to colistin or tigecycline. A total of eight sequence types (STs) were detected in these CRKPs, with ST11 (39/59) and ST15 (12/59) being the most common. Among the carbapenemase genes, <i>bla</i>_KPC (39/59) and <i>bla</i>_NDM (18/59) were the most common, with <i>bla</i>_KPC-2 transmitted mainly through ST11 clones and <i>bla</i>_NDM-5 transmitted through ST15 clones. The <i>bla</i>_NDM-harboring plasmids primarily belong to the incompatibility type IncX3 (14/18). IS<i>26</i>-mediated gene recombination, sequence insertion, and plasmid integration were observed to occur during the dissemination process. The resistance gene profile mediated by <i>bla</i>_NDM-harboring plasmids can be transferred through conjugation, which have almost no fitness cost and is extremely stable after passage. Six of these strains presented carbapenem resistance combined with hypervirulence (CR-hvKP), including ST23-KL1, ST218-KL57, ST17-KL112, and ST147-KL64. Additionally, <i>bla</i>_NDM-harboring plasmids can disseminate rapidly over large surface areas and persist for a long time in medical institutions, leading to outbreaks of highly resistant clones associated with CR-hvKP.IMPORTANCEThe appearance of plasmids carrying <i>bla</i>_NDM and the rise of carbapenem-resistant hypervirulent <i>Klebsiella pneumoniae</i> (CR-hvKP) have significantly escalated the public health risk associated with Carbapenem-resistant <i>Klebsiella pneumoniae</i> (CRKP). In this study, we described the resistance rates, virulence factors, and molecular epidemiology of 59 CRKP isolated from patients at a tertiary hospital in China from 2019 to 2021. Beyond this, we also assessed the characteristics of <i>bla</i>_NDM-harboring plasmids and their dissemination patterns among CRKP, especially some CR-hvKP. Our research contributes to the field of <i>bla</i>_NDM dissemination studies, prompting researchers to formulate strict measures to prevent and control the development of <i>bla</i>_NDM-harboring plasmids, which is instrumental in the clinical development of targeted treatment plans.