Pathogenicity Analysis of a PVL+ST22 Staphylococcus aureus Isolated from Equine Raw Milk
There are few reports on PVL+ST22 Staphylococcus aureus(S.aureus)isolated from equine milk in China.This study was conducted to evaluate the pathogenicity of an S.aureus(PVL+ST22)isolated from equine milk in Xinjiang,hoping to provide basic data for the study of S.aureus from equine milk in China.S.aureus were isolated from apparently healthy equine milk in Xinjiang using the selective medium and then identified by biochemical and molecular identification methods.The obtained S.aureus were subjected to multilocus sequence typing(MLST),spa typing,antimicrobial susceptibility testing,and biofilm-forming ability,hemolytic activity,virulence gene detection,along with mouse skin abscess and pathogenicity assay.The isolated strain was then subjected to mouse macrophage adhesion,invasion,and intracellular pro-liferation assays to assess their pathogenicity.The results indicated that a PVL+ST22 S.aureus(1/65,1.5％)strain was isolated from equine milk,with spa typing t304.It was resistant to penicillin only,had no biofilm-forming ability,but carried 9 virulence genes(sec,seg,seh,tsst-1,hla,hilb,clfA,clfB,and cna)and has hemolytic activity.Mouse skin abscess and pathoge-nicity tests also showed that it caused skin abscess formation and death in mice at high doses of infection.ST22 S.aureus has adhered(4.26％),invaded(6.45％),and proliferated intracellu-larly in mouse macrophages and caused apoptosis.In conclusion,the PVL+ST22 S.aureus iso-lated from equine milk is highly pathogenic and may pose potential risks in terms of host pathoge-nicity and public health safety.
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维普
