Comparison of the ability of Staphylococcus aureus strains to adhere to and invade 293 cells

Objective To test the invasion ability of different Staphylococcus aureus（S.aureus）strains. Methods S.aureus strains were incubated with 293 cells at 37℃to infect the 293 cells.Two hours after infection,the medium was replaced with DMEM containing 10μg/mL lysostaphin to kill the S.aureus strains in extra-cellular cells.The cells were trypsinized and lysed with trypsin EDTA and Triton X-100 solution.Cell lysate and supernatant were appropriately diluted and plated on LB agar plates,and colony forming units（CFU）were quantified. Results Clinical isolates of S.aureus 04018 strain had a strong ability to invade 293 cells. Conclusion The ability of S.aureus strains to invade 293 cells by mediating expression of fibronectin-binding protein-FnBP.Different strains have different expression levels and invasion abilities.However,in addition to FnBP protein,other factors may be involved in the invasion of 293 cells.