Phenotype and genotype of carbapenem-resistant hypervirulent Klebsiella pneumoniae in a teaching hospital in Shanghai, China.

Introduction. Carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) is an emerging pathogen associated with severe clinical outcomes, prompting an urgent investigation into its genomic characteristics and pathogenic potential.Hypothesis/Gap Statement. We hypothesize that CR-hvKP strains exhibit high-level resistance and high virulence, leading to their rapid spread in clinical settings and posing a serious threat to clinical treatment.Aim. The aim of the study was to investigate the phenotype and genotype of CR-hvKP strains, reveal their resistance- and virulence-related genomic characteristics and elucidate the biological characteristics of high-virulence and high-resistance strains to provide molecular epidemiological data for clinical use.Methodology. Carbapenem-resistant K. pneumoniae (CRKP) strains were obtained from clinical samples, from January 2013 to December 2018. PCR amplification was conducted to screen for carbapenem genes. To evaluate the virulence potential of the isolates, we conducted various tests, including a string test, Galleria mellonella larvae infection test, capsular polysaccharide synthesis genotyping and genetic sequencing analyses. We used PFGE, multilocus sequence typing and next-generation sequencing to detect the genetic relationship and homology of the strains.Results. In this study, we obtained 500 strains of CRKP, among which 18 strains were identified as CR-hvKP. All CR-hvKP strains were multidrug-resistant, exhibiting high-level resistance to most β-lactam antibiotics, including carbapenems. All CR-hvKP strains except N5 were positive for blaKPC-2, of which 14 isolates belonged to capsular serotype K64. Ten unrelated PFGE types were identified by PFGE analysis. Based on the results of PFGE, a total of 12 CR-hvKP isolates were selected from the 18 isolates for further testing, and 9 isolates had high homology with pLVPK virulence-related plasmids. All CR-hvKP strains showed high virulence in the Galleria mellonella infection model.Conclusions. The study revealed the resistance- and virulence-related genomic characteristics of CR-hvKP strains and confirmed the high virulence of these strains. These results are of great significance for understanding the epidemiological characteristics and clinical treatment of CR-hvKP and provide basic data for the formulation of corresponding prevention and control strategies.