Whole-genome sequencing and virulence characteristics of Klebsiella variicola
Objective To perform whole-genome sequencing of Klebsiella variicola and virulence experiments of Galleria mellonella,in order to provide reference for the study of molecular virulence characteristics of Klebsiella variicola.Methods A total of three strains of Klebsiella variicola isolated from patients blood in the Affliated Central Hospital of Jiangnan University from January to December 2021 were collected,to perform the species identification and whole-genome sequencing.The difference of lgLD50 of Galleria mellonella infection model was used to analyze the virulence of Klebsiella variicola.Results The three strains of Klebsiella variicola could be identified by Vitek MS V3.2,and the characteristic peak was found at 8 250 m/z in all the mass spectra.The string test showed that the wxkv2055 was positive.The dug susceptibility test showed that wxkv2055 and wxkv2031 were only resistant to ampicillin and sensitive to other antibiotics,while wxkv2096 was resistant to ampicillin,ciprofloxacin,levofloxacin,amikacin,gentamicin,and trimethoprim/sulfamethoxazole.The whole genome sequencing showed that the GC contents of the three strains were 56.8％-57.2％,the capsular serotypes included KL14,KL16,KL34,the O antigen typing included O5,O3/O3a,and the MLST typing included 1169,595,and 718.The wxkv2055 carries a 23.81 kb IncHI1B virulence plasmid.The virulence model analysis of Galleria mellonella showed that the lgLD50 of wxkv2055 was significantly lower than that of wxkv2031 and wxkv2096(both P<0.05),the lgLD50 of wxkv2055 was not statistically different from that of the control hypervirulent bacteria NTUH-K2044(P>0.05).Conclusions The Klebsiella variicola wxkv2055 isolated from blood carries virulence plasmid.The Galleria mellonella virulence model indicated that the virulence of wxkv2055 is higher.The molecular epidemiology of three strains of Klebsiella variicola is different from Klebsiella pneumoniae.At present,the grassroots laboratories need to improve the ability to identify Klebsiella variicola,conduct in-depth research on the pathogenicity and strain characteristics of Klebsiella variicola,and provide guidance for clinical diagnosis and treatment.
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