溶葡萄球菌酶对耐甲氧西林金黄色葡萄球菌的体外抗菌活性

目的 :探讨溶葡萄球菌酶对万古霉素低敏耐甲氧西林金黄色葡萄球菌 (MRSA)的抗菌活性。方法 :琼脂稀释法测定万古霉素和溶葡萄球菌酶对MRSA的最低抑菌浓度 (MIC) ,棋盘法检测 2药联合抑菌作用。结果 :万古霉素对其敏感或低敏MR SA的MIC90 分别为 2mg·L- 1,8mg·L- 1;溶葡萄球菌酶对万古霉素敏感或低敏MRSA的MIC90 分别为 0 .2 5mg·L- 1,0 .5mg·L- 1;2药联合对其敏感株和低敏株的FIC90 (FIC为联合抑菌分数 )较万古霉素单独应用时MIC90 分别减少 4倍和 8倍 ,较溶葡萄球菌酶单独应用时均减少 4倍。FIC指数均小于0 .5。结论 :溶葡萄球菌酶对万古霉素敏感或低敏的MRSA均有良好的体外抗菌活性

Antimicrobial activity in vitro of lysostaphin against methicillin-resistant Staphylococcus aureus

AIM: To investigate the antimicrobial activity of lysostaphin against methicillin-resistant Staphylococcus aureus (MRSA) with reduced susceptibility to vancomycin. METHODS: The minimal inhibitory concentration(MIC) of vancomycin and lysostaphin were detected by agar dilution.The fraction inhibited concentration (FIC) of vancomycin and lysostaphin in combination was tested by the checkerboard method and FIC index was counted. RESULTS: MIC 90 of vancomycin against MRSA with sensitive or low susceptibility to it were 2 mg·L -1 and 8 mg·L -1, respectively. MIC 90 of lysos-taphin against MRSA with sensitive or low suscepitibility to vancomycin were 0.25 mg·L -1 and 0.5 mg·L -1, respectively. The FIC 90 of vancomycin combined with lysostaphin against MRSA with sensitive or reduced susceptibility to vancomycin were 4-fold and 8-fold,respectively, as low as the MIC 90 of it alone. FIC 90 of lysostaphin combined with vancomycin against MRSA with sensitive or reduced susceptibility to vancomycin were 4-fold as low as the MIC 90 of lysostaphin alone. The FIC index of vancomycin and lysostaphin in combination were all less than 0.5. CONCLUSION: Lysostaphin has a powerful antimicrobial activity in vitro against MRSA with sensitive or reduced susceptibility to vancomycin.