The observation of bovine mammary epithelial cells infected with Staphylococcus aureus small colony mutant in vitro

SHI Yongqiang;ZHU Yu;GONG Lei;LU Lu;YAN Xingqiong;QU Weijie;College of Animal Science and Technology,Yunnan Agricultural University;

Staphylococcus aureus small colony mutant;;Staphylococcus aureus quality control strain ATCC25923;;bovine mammary epithelial cell;;invasion;;common light microscopy;;scanning electron microscopy

In order to study the invasion effect of Staphylococcus aureus small mutant on normal bovine mammary epithelial cells,using common light microscopy and scanning electron microscopy,a clinical isolated mutant and the quality control strain ATCC25923 of Staphylococcus aureus were tested in this experiment to infect bovine mammary epithelial cells for the ovservation of morphologic changes on epithelial cells and of invasion process of bacteria to cells. The results showed that both the mutant and ATCC25923 quality control strains led to apoptosis in mammary epithelial cells 3 h post infection,with cell volume decreased,cell nucleolus concentrated,nuclear membrane and nucleolus broken,and also with small vesicle formation on cell membrane. The results suggested that the Staphylococcus aureus small mutant was pathogenic to bovine mammary epithelial cells but far below the pathogenicity of the quality control strain ATCC25923. The small mutant could exist persistently in bovine mammary epithelial cells,with a certain proportion of bacteria survival in the cells. This small mutant had a lower invasion ability to the cells compared with the quality control strain ATCC25923.