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Virulence. 2018 Jan 1;9(1):510-521. doi: 10.1080/21505594.2017.1421894.

Whole-Genome-Sequencing characterization of bloodstream infection-causing hypervirulent Klebsiella pneumoniae of capsular serotype K2 and ST374.

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a Department of Critical Care Medicine , Ruijin Hospital, Shanghai Jiao Tong University School of Medicine , Shanghai , China.
b State Key Laboratory of Microbial Metabolism , Joint International Laboratory of Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University , Shanghai , China.
c Department of Laboratory Medicine , Jinshan Hospital, Shanghai Medical College, Fudan University , Shanghai , China.
d Department of Laboratory Medicine , Huashan Hospital, Shanghai Medical College, Fudan University , Shanghai , China.
e Department of Clinical Microbiology , Ruijin Hospital, Shanghai Jiaotong University School of Medicine , Shanghai , China.


Hypervirulent K. pneumoniae variants (hvKP) have been increasingly reported worldwide, causing metastasis of severe infections such as liver abscesses and bacteremia. The capsular serotype K2 hvKP strains show diverse multi-locus sequence types (MLSTs), but with limited genetics and virulence information. In this study, we report a hypermucoviscous K. pneumoniae strain, RJF293, isolated from a human bloodstream sample in a Chinese hospital. It caused a metastatic infection and fatal septic shock in a critical patient. The microbiological features and genetic background were investigated with multiple approaches. The Strain RJF293 was determined to be multilocis sequence type (ST) 374 and serotype K2, displayed a median lethal dose (LD50) of 1.5 × 102 CFU in BALB/c mice and was as virulent as the ST23 K1 serotype hvKP strain NTUH-K2044 in a mouse lethality assay. Whole genome sequencing revealed that the RJF293 genome codes for 32 putative virulence factors and exhibits a unique presence/absence pattern in comparison to the other 105 completely sequenced K. pneumoniae genomes. Whole genome SNP-based phylogenetic analysis revealed that strain RJF293 formed a single clade, distant from those containing either ST66 or ST86 hvKP. Compared to the other sequenced hvKP chromosomes, RJF293 contains several strain-variable regions, including one prophage, one ICEKp1 family integrative and conjugative element and six large genomic islands. The sequencing of the first complete genome of an ST374 K2 hvKP clinical strain should reinforce our understanding of the epidemiology and virulence mechanisms of this bloodstream infection-causing hvKP with clinical significance.


Klebsiella pneumoniae; ST374; bloodstream infection; capsular serotype K2; comparative genomic analysis; hypervirulent

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