Abstract: In order to determine whether there were pathogenic bacteria in cow bedding and to further understand the types,drug resistance and pathogenicity of dominant growth bacteria in bedding,bacterial isolation and culture,Gram staining microscopy,biochemical test identification,16S rDNA sequence analysis and homology comparison,drug sensitivity test,pathogenicity test in mice were carried out.The results showed that the isolated bacteria formed round and smooth white colonies on the nutrient agar medium,while thick and large white colonies were formed on the blood nutrient agar medium.The results of Gam staining microscopy showed that the isolate was Gram-positive,spherical,arranged in clusters of grapes or scattered individually.The results of biochemical tests showed that the reaction of xylose,glucose,maltose,fructose,lactose and nitrate were positive,while melibiose,xylitol,sorbitol,urea and V-P test were negative.The 16S rDNA sequence analysis results showed that the nucleotide sequence of 16S rDNA was 1 298 bp,99.85% to 100% homology with Staphylococcus sciuri.The phylogenetic tree showed that the isolate was clustered Staphylococcus sciuri.The animal experiments showed that the isolated bacterium had strong pathagenicity to mice,the mortality was 60% when inoculated with 0.2 mL 7.9×10⁸ CFU/mL isolated strain in 48 h.Drug resistance analysis showed that the isolate was sensitive to 7 drugs,such as sulfamethoxazole,ampicillin,moderately sensitive to clindamycin,cefotaxime and cefuroxime,resistant to penicillin,erythromycin and lincomycin.This study could provide a reference for identification and prevention of Staphylococcus sciuri.

Key words: Staphylococcus sciuri; dairy cow; 16S rDNA; drug sensitivity analysis