Abstract: We studied the antibacterial effects and mechanism of extracts from Orostachys cartilaginous A.Bor on Salmonella typhoon and Shigella dysenteric. The experimental results show that there are obvious antibacterial effects of ethyl acetate, petroleum ether and chloroform phases on S.typhoon and S.dysenteric. Compared with the control group, the difference is very significant (p<0.01). The minimum inhibitory mass concentration (MIC) of the extracts on the experimental bacteria are obviously different. The MIC of ethyl acetate and petroleum ether extract on S.typhoon are 1.5 mg/mL, and the MIC of ethyl acetate on S.dysenteric is 1 mg/mL. O.cartilaginous A.Bor may inhibit growth of S.typhoon and S.
dysenteric by interfering with the synthesis of cytoderm and inhibition of biofilm formation. The antibacterial effects increase with the increase
of the mass concentration of the extract and the prolonging of the action time.

Key words: antibacterial effect, Shigella dysenteric, Salmonella typhoon, Orostachys cartilaginous A.Bor