不同中药提取物对耐甲氧西林金黄色葡萄球菌的抑菌作用和逆转机制

Effect of different kinds of Chinese traditional medicine extracts against methicillin-resistant Staphylococcus aureus in vitro

采用(K-B)药敏纸片扩散法检测耐甲氧西林金黄色葡萄球菌(MRSA)的药物敏感性,并用二倍稀释法分别测定10种中药提取物对MRSA的最小抑菌浓度(MIC)和最小杀菌浓度(MBC),选取抑菌效果最好的中药提取物(黄芩)通过棋盘法测定其与5种常用抗生素的联合抑菌效果。观察黄芩不同亚抑菌浓度作用下对MRSA耐药性的逆转效果,并通过荧光实时定量PCR法检测耐药基因mec A在mRNA表达水平上的变化。结果表明,MRSA具有多重耐药性,10种中药提取物里黄芩的抑菌和杀菌效果最为显著,MIC和MBC均为156 mg/L,但其与5种抗生素没有显著的联合抗菌作用,在黄芩亚抑菌浓度130 mg/L作用20 h后,MRSA主要耐药基因mec A的表达量下调并恢复了对药物的相对敏感性。

The drug susceptibility of methicillin-resistant Staphylococcus aureus （MRSA） were per- formed by Kirby-Bauer method, the antimicrobial activities of 10 kinds of Chinese traditional medi- cine extracts were evaluated by minimal inhibitory concentration（MIC） and minimal bactericidal concentration（MBC）, the one of which have the best antimierobial activities was chosen to combined with 5 antibiotics respectively,and effects of drug combinations were tested with the chess- board method. The reverse effect of MRSA were investigated on different subinhibitory concentration of Astragalus, and the mRNA expression of mecca gene were analyzed with real-time quantitative PCR. The results showed that the MRSA had multiple drug tolerance,Astragalus had a better antibacterial effect than the others,its MIC and MBC were both 156 mg/L,but it didn＇t have any combination effect with the 5 antibiotics. When MRSA incubated on 130 mg/L of Astragalus subinhibitory concentration for 20 hours,the expression of mecA was down-regulated and MRSA recovered its drug sensitivity relatively.