Emergence of ST23-K1 blaKPC-3-positive hypervirulent carbapenem-resistant Klebsiella pneumoniae from China: A molecular, biological, and epidemiological study

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• The Hv-CRKP from China was ST23 with K1 capsule, which contains four plasmids. • The genetic environment of blaKPC-3 in plasmid 2 was IS26-ISKpn27- bla KPC-3 -Tn21. • The resistance plasmid of Kpn_24-5 strain was transferable. • The strain has higher tolerance to neutrophils, is not easily inhibited by serum. Objective: A highly virulent Klebsiella pneumoniae ST23-K1 carrying bla KPC-3 , named as Kpn_24-5, was identified in the blood samples of a patient with multiple complications. We investigated the transfer and pathogenic mechanism of this strain, and elucidated the epidemiological situation of the strain. Methods: A bla KPC-3- positive ST23-K1 K. pneumoniae was isolated. Antimicrobial susceptibility test and whole genome sequencing were used to study the phenotypes and genotypes of the strain. The transmission and pathogenic mechanism were investigated by means of conjugation transfer test, neutrophil killing test, and serum inhibition test. Results: The Kpn_24-5 strain was ST23 serotype with K1 capsule, which contains four plasmids. Plasmid 1 carries several virulence genes, belonging to the same clade as K. pneumoniae plasmid isolated from the USA in 2023. Plasmid 2 is an anti-plasmid containing bla KPC-3 carbapenem resistance gene, belonging to the same clade as K. pneumoniae plasmid isolated from China in 2024. The genetic characteristics of plasmids indicated that the genetic environment of bla KPC-3 in plasmid 2 of Kpn_24-5 strain was IS26-ISKpn27- bla KPC-3 -Tn21. The resistance plasmid 2 of Kpn_24-5 strain was transferable. The Kpn_24-5 strain has higher tolerance to neutrophils, is not easily inhibited by serum, and has significantly higher infectivity. Conclusions: The present study corroborates the emergence of hypervirulent CR-hvKP in the Zhejiang region, a phenomenon that is presumably attributable to the acquisition of an IncFIB virulence plasmid and a bla KPC-3 resistance plasmid by the ST23-K1 type K. pneumoniae . Our findings highlight the urgent need to use antibiotics more wisely to limit the emergence of resistance.

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