Biological Characterisitcs And Pathogenicity Analysis Of Klebsiella Pneumoniae From Mink

Klebsiella pneumoniae,a conditional pathogens that can cause a variety of diseases in humans and animals,often parasitic respiratory tract,digestive tract and genitourinary tract of humans and anminals.In this study,we isolated and identified the Klebsiella pneumoniae of mink and analyzed its pathogenicity,our study aimed to provide reference for the prevention and detection of Klebsiella pneumoniae in fur animal.1.Isolation and identification of Klebsiella pneumoniae from minkFrom 2015 to 2018,we performed bacterial isolation and identification on the lungs of mink with respiratory illnesses mink in Shandong,Liaoning and Heilongjiang province.Thirty-one strains of Klebsiella pneumoniae were isolated from 168 samples by morphological observation,the separation rate was 18.4%.Vitek automatic bacterial identification instrument,16S rRNA and khe gene identification.There were 3 strains of K2 and 1 strain of K54.Only one strain had strong biofilm production ability.A total of 20 strains showed multiple drug resistance to commonly used antibiotics.The PCR were performed to amplify 10 resistant genes,The detection rates of TEM,SHV,CTX-M,AcrAB,tolC,mdtk,OmpK35,gyrA and parC were 71%?22/31?,81%?25/31?,39%?12/31?,90%?28/31?,90%?28/31?,61%?19/31?,84%?26/31?,77%?24/31?and 84%?26/31?,respectively.However,OmpK36 gene was not detected.And 2 strains contained 9 drug-resistant genes,and 13 strains contained 8 drug-resistant genes.The results showed that the fim 23%?7/31?,ureA 77%?24/31?,wabG68%?21/31?,rmpA 10%?3/31?,kfu 13%?4/31?,alls 16%?5/31?,iucB 13%?4/31?,uge 48%?15/31?and Ab 10%?3/31?,only 1 positive ybtA gene,but the iroNB gene gave a negative PCR reaction.Three strains of positive rmpA and Ab gene were dectecd,and the three strains were K2 serotype and high mucous phenotype,respectively Kp-SD-11,Kp-SD-16 and Kp-SD-18 strains.2.Pathogenicity study of Klebsiella pneumoniae from minkIn this study,three strains of Kp-SD-11?K2?,Kp-SD-16?K2?and Kp-DL-33?K54?were selected on the basis of the serum type,virulence gene and hyperviscosity phenotype of the isolated strain,and LD₅₀,artificial infection test and pathological tissue sections were performed.5⁶ h hours after the artificial infection,the mice in the experimental group began to show brick-red secretion in the corner of the eyes.The dead mice showed that there was a large amount of mucus-like substance in the abdominal cavity,and there were bleeding spots in the liver,spleen and lung,especially in the lung and spleen.Twelve hours after the infection,the experimental group began to die successively.The dead mink showed hemorrhagic spots in liver,spleen,lung and trachea.The alveolar wall thickened and congestion were observed by histopathology.Congestion of liver,spleen and kidney.The LD₅₀ of the three strains for mice were 9.4×10^2.5 CFU,9.8×10^2.3 CFU and 1.7×10⁵.8.8 CFU,respectively.The LD₅₀ of mink were 9.4×10^4.2 CFU,9.8×10^4.8 CFU and 1.7×10⁷.8.8 CFU,respectively.Klebsiella pneumoniae could be isolated from the viscera of dead mice and mink.It was confirmed that K2 serotype Klebsiella pneumoniae was more virulent than K54 serotype and had higher pathogenicity,which provided basic data for establishing the pathogenicity model of Klebsiella pneumoniae on mice and mink.