Objective: To study antibacterial active fraction of Bletilla striata against methicillin-resistant Staphylococccus aureus(MRSA). Method: Minimum inhibitory concentrations (MICs) of ethyl acetate extract

n-butanol extract

water extract after extraction and water decoction after extracting alcohol from B. striata against MRSA and S. aureus(MSSA) was assayed. Oral administration and intraperitoneal injection of ethyl acetate extract from B. striata were given to mice before they are infected by MRSA. Result: Ethyl acetate extract and n-butanol extract showed obvious antibacterial activity. Ethyl acetate extract had the highest activity with MIC 0.065-0.26 g·L-1. Ethyl acetate extract could completely protect mice from MRSA through intraperitoneal injection with the concentration of 0.5 g·kg-1. Conclusion: Ethyl acetate extract is the main active fraction of B. striata against MRSA and MSSA.