Abstract: ObjectiveTo determine the cytotoxicity of EHEC O₁₅₇:H₇ 97-1-68 strain (Zhejiang strain) with Vero,HeLa,CHO,and KMB17 cell-lines and compare it with other strains.MethodsBacterial supersonic lysates and culture supernatants were tested for cytotoxic activity with monolayer cells in microtitre tissue culture trays.ResultsThe cytotoxicities of 97-1-68 strain were negative all against the four cell-lines while the positive reference strains had high titers of cytotoxicity against Vero and HeLa cell-lines.ConclusionA viewpoint on "Two Sorts of Strains" in EHEC O₁₅₇:H₇ infections was put forward.