万古霉素联合用药降低对金黄色葡萄球菌防耐药突变浓度的研究

Studies for decreasing mutant prevention concentration of Staphylococcus aureus by combination of vancomycin and other antibiotics in vitro

目的体外研究万古霉素(vancomycin,VAN)分别与左氧氟沙星(levofloxacin,LVX)、利福平(rifampincin,RFP)、磷霉素(fosfomycin,FOM)联用对降低对金黄色葡萄球菌防耐药突变浓度(MPC)的比较,为指导临床联合应用抗菌药物,制定新的用药策略,防止细菌耐药产生提供理论依据。方法采用肉汤富集1010CFU/mL金黄色葡萄球菌ATCC29213,采用琼脂平板二倍稀释法测定单独用药的最低抑菌浓度(MIC),琼脂平板稀释法测定单独应用VAN以及与其他三种药物联用对金黄色葡萄球菌ATCC29213的MPC。并计算出各药单独应用的MSW(MPC/MIC)。结果 VAN、LVX、RFP、FOM单药对金黄色葡萄球菌ATCC29213的MIC分别为1,0.125,0.008和2μg/mL;MPC分别为64,2,>32,64μg/mL,MSW为64,6,>4000,32。联合用药后各药的MPC(μg/mL)降低程度如下:VAN+LVX(MPCNVA–4,MPCLVX–0.125),VAN+RFP(MPCNVA–4,MPCRFP–0.008),VAN+FOM(MPCNVA-1,MPCFOM-2)。联合LVX和RFP可使VAN的MPC降至原来的1/16倍,联合FOM可使VAN的MPC降至原来的1/64倍。结论 VAN与另三种药物联用,可以明显降低各自单独用药对金黄色葡萄球菌ATCC29213的MPC,其中联合FOM降低其MPC幅度最大,缩小其MSW效果最好。

Objective To study the comparison of Vancomycin （VAN） separately combined with levofloxacin （LVX）, rifampincin （RFP） and fosfomycin （FOM） for decreasing mutant prevention concentration （MPC） of Staphylococcus aureus in vitro, which direct rational applications of available antibiotics in clinic practice and provide evidence for new strategies for restricting the development of resistance. Methods The Staphylococcus aureus strain ATCC29213 was enriched the concentration to 10^10 colony forming units per milliliter in broth. Minimum inhibitory concentration （MIC） of VAN, LVX, RFP and FOM alone was determined by agar plates dilution method. Mutant prevention concentration （MPC） of each single and combined was carried out by agar plates dilution method.Then mutant selection window（MSW） could be caculated. Results MIC of VAN, LVX, RFP and FOM for Staphylococcus aureus strain ATCC29213 separately were 1, 0.125, 0.008, 2μg/mL; MPC of these four antibiotics alone were 64, 2, 〉32, 64 μg/mL; and MSW（MPC/MIC） of each antibiotic were 64, 16, 〉4000, 32; after combinated MPC（μg/mL） of each alone were decreased as fllows： VAN＋LVX （MPCNVA-4, MPCLVX-0.125）, VAN＋RFP（MPCNVA-4, MPCRFP-0.008）, VAN＋FOM（MPCNVA -1, MPCFOM -2 ）. MPCNVA of VAN combined with LVX can decrease to 1/16 times of VAN used alone. MPCNVA of VAN combined with RFP can decrease to 1/16 times of it used alone either. MPCNVA of VAN combined with FOM can decrease to 1/64 times of it used alone. Conclusion Compared with each one alone, the combination of VAN separately with other three antibiotics can obviously decrease MPCVAN. The combination of VAN and FOM was more evidently in dropping MPCNVA of Staphylococcus aureus strain ATCC29213 and narrowing MSW of VAN.