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Objective:To screen traditional Chinese medicine with powerful antibacterial activity against methicillin-resistant Staphylococcus aureu (MRSA) from 50 Chinese medicine in common use, and provide basis of Chinese herbal preparation against MRSA.Methods:50 Chinese medicine in common use were smashed in to coarse powder after drying, and then decocted by water, concentrated, centrifuged, and made into sterile solution after sterile filtration.1 ml of solution was equivalent to 1 g dried medicinal herbs. The bacterial strain of MARS provided by clinical examination centre of our hospital were recovered, identified and reproduced. The Chinese medicines with powerful antibacterial activity against MRSA were selected from 50 traditional Chinese medicines by Kirby-Bauer, and 5 Chinese medicines with most powerful antibacterial activity against MRSA were selected to carry on further research. The MICs of selected Chinese medicines with most powerful antibacterial activity against MRSA were performed according to liquid dilution method recommended by national committee for clinical laboratory standards. Bactericidal actions of the selected Chinese medicines were observed and killing curves of MRSA were drawn. Synergetic antibacterial test of each two of the selected 5 Chinese medicines against MRSA were carried out by trace multi-well culture plates.Results:35 Chinese medicines had inhibitory effects on the strain of MRSA with varied extent in 50 Chinese medicines, among which Coptis chinensis, Cortex Phellodendri, Rhubarb, Radix Stellariae and granatum had the most powerful effects respectively with the bacteriostatic diameter of 18.2±1.2 mm,17.5±1.5 mm,16.4±1.5 mm,15.3±1.4 mm and 14.6±1.2 mm. The mean MICs of Coptis chinensis, Cortex Phellodendri, Rhubarb, Radix Stellariae and granatum were resectively 0.0125 g/mL,0.00365 g/mL,0.00625 g/mL, 0.05g/mL and 0.045 g/mL. Coptis chinensis, Cortex Phellodendri, Rhubarb, Radix Stellariae and granatum could kill bacterial strain of MARS with varied extent, and made the amount of bacterial strain of MARS not increased in 12 hours and had powerful antibiosis effects. Furthermore, FIC index of Coptis chinensis and Cortex Phellodendri was below 0.5,so their interactions were synergetic.Conclusion:(1) Coptis chinensis, Cortex Phellodendri, Rhubarb, Radix Stellariae and granatum have powerful antibacterial activity against MRSA. (2) The mean MICs of Coptis chinensis, Cortex Phellodendri, Rhubarb, Radix Stellariae and granatum were resectively 0.0125 g/mL,0.00365 g/mL,0.00625 g/mL,0.05g/mL and 0.045 g/mL (3) Coptis chinensis, Cortex Phellodendri, Rhubarb, Radix Stellariae and granatum could kill bacterial strain of MARS with varied extent. (4) Combined use of Coptis chinensis and Cortex Phellodendri has the most inhibitory effect on MRSA because of synergistic effect, and are the good choice in anti-MRSA Chinese medicines.
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