夫西地酸联合黄芩素对金黄色葡萄球菌的体内外抗菌作用研究

Antibacterial effect of fusidic acid combined with baicalein on Staphylococcus aureus in vitro and in vivo

目的研究夫西地酸(fusidic acid,FA)联合黄芩素(baicalein,BE)在体内和体外对13株金黄色葡萄球菌的抗菌特性。方法采用微量肉汤稀释法和微量棋盘法测定最小抑菌浓度(minimum inhibitory concentration,MIC)和部分抑菌浓度指数(fractional inhibitory concentration index,FICI)。采用FICI评价综合效果,采用时间-杀菌曲线法测定杀菌效果。利用琼脂二倍稀释法对5株金黄色葡萄球菌的防耐药突变浓度(mutant prevention concentration,MPC)和防耐药突变选择窗(mutant selective window,MSW)进行测定,比较夫西地酸单独应用及联用黄芩素后防耐药突变窗的变化。使用金黄色葡萄球菌感染肺炎小鼠模型进行体内实验,测定FA和BE单独和联合治疗后生命体征、肺脏指数、菌落定植数和血清炎症因子的变化。结果研究发现,FA与BE组合的协同效应为53.8%,相加效应为30.8%,无关效应为15.4%。此外,研究人员观察到,当FA与BE以特定浓度(分别为1MIC和1/2MIC)结合时,在24h后对3株金黄色葡萄球菌(SA-ATCC29213、MRSA-ATCC43300和MRSA-210702212)均有杀菌作用。FA对这些菌株的MPCs为128~256μg/mL,而MSWs为64~256μg/mL。而当BE加入混合物时,菌株的MPCs降低到16~32μg/mL,MSWs降低了8~16倍,说明BE提高了FA对这些菌株的抗菌活性。FA和BE的组合对金黄色葡萄球菌肺炎小鼠的生命体征影响很小。小鼠肺脏指数、肺部金黄色葡萄球菌定植数、血清中炎症因子等实验结果表明,FA和BE组合对金黄色葡萄球菌的影响很小,但联合用药组对小鼠肺炎的治疗效果明显优于单药组。结论FA单独应用时,MSW较宽,联用BE后,FA的MSW明显缩小。FA联合BE有协同杀菌效应,治疗小鼠金葡菌肺炎效果较单药组好。

Objective To investigate the antibacterial properties of fusidic acid(FA)in combination with baicalein(BE)against 13 strains of Staphylococcus aureus(SA)both in vivo and in vitro.Methods The minimum inhibitory concentration(MIC)and fractional inhibitory concentration index(FICI)were determined using the microbroth dilution method and the micro checkerboard method.The FICI was used to evaluate the comprehensive effect,while the bactericidal effect was determined using the time-killing curve method.The mutant prevention concentration(MPC)and the mutant selective window(MSW)were determined using the agar double dilution method for the comparison of the change in mutation window of drug resistance after adminstration of FA alone and in combination with BE.In vivo experiments were conducted using a mouse model of pneumonia infected with SA,and the changes in vital signs,lung organ index,colony colonization number,and serum inflammatory factors were measured following single and combined treatment with FA and BE.Results The study found that the combination of FA and BE had a synergistic effect of 53.8%,an additive effect of 30.8%,and an irrelevant effect of 15.4%.Furthermore,the researchers observed that when FA was combined with BE at specific concentrations(1 MIC and 1/2 MIC,respectively),it had a bactericidal effect on three strains of SA(SA-ATCC29213,MRSA-ATCC43300,and MRSA-210702212)after 24 hours.The MPCs of FA for these strains ranged from 128~256μg/mL,while the MSWs ranged from 64~256μg/mL.However,when BE was added to the mix,the MPCs of the strains decreased to 16~32μg/mL and the MSWs were reduced by 8~16 times,indicating that BE enhanced the antimicrobial activity of FA against these strains.The combination of FA and BE had minimal impact on the vital signs of mice with SA pneumonia.The experiment showed that the combination of FA and BE had little effect on the lung organ index as well as on the colony colonization number of SA in the lungs and serum inflammatory factors.However,the therapeutic effect on mouse pneumonia was significantly better when compared to the single-drug group.Conclusion The MSW of FA was wider when applied alone,and the MSW of FA was significantly reduced after combined with BE.FA combined with BE has a synergistic bactericidal effect,which is better than a single drug group in the treatment of SA pneumonia.