lycosin-Ⅰ体外抗耐甲氧西林金黄色葡萄球菌活性及联合药敏试验

In vitro efficacy and combined drug sensitivity of lycosin-I against methicillin-resistant Staphylococcus aureus

目的探究lycosin-Ⅰ体外抗耐甲氧西林金黄色葡萄球菌(MRSA)的活性及体外联合8种常用抗菌药物对MRSA的抗菌作用。方法本研究遵循了随机对照试验的设计原则。收集中南大学湘雅二医院2021年9至11月临床分离的MRSA 10株,采用微量肉汤稀释法测定lycosin-Ⅰ体外抗MRSA的最低抑菌浓度(MIC)、最小杀菌浓度(MBC)和杀菌动力学试验;采用微量肉汤棋盘式稀释法检测lycosin-Ⅰ与青霉素、红霉素、左氧氟沙星、庆大霉素、利福平、米诺环素、万古霉素及利奈唑胺共8种常见抗菌药物的体外联合抑菌效果。结果lycosin-Ⅰ体外抗MRSA的MIC范围为4~8 mg/L,MIC50和MIC90分别为4和8 mg/L;MBC范围为4~8 mg/L,其比值MBC/MIC为1~2;杀菌动力学试验结果显示,lycosin-Ⅰ浓度为1/2 MIC或MIC时,MRSA临床分离株和标准菌株均在短时间存活菌数下降而后出现恢复繁殖的现象,而浓度为2 MIC或4 MIC时存活细菌载量则呈现逐渐减少直至杀灭的趋势。lycosin-Ⅰ与庆大霉素体外联用时以协同作用为主而与其他抗菌药物联用主要表现为相加作用。此外,lycosin-Ⅰ与抗菌药物体外联用后可显著降低抗菌药物的MIC50和MIC90。结论lycosin-Ⅰ在体外对MRSA具有较好的抑菌和杀菌活性且杀菌快速、彻底,同时与其他抗菌药物体外联合抗MRSA时,能起到协同或相加作用。

Objective The aim of this study was to evaluate the in vitro activity of lysosin-Ⅰagainst Methicillin-resistant Staphylococcus aureus(MRSA)and its synergistic effect with eight common antibacterial drugs against MRSA.Methods This study was conducted following the design principles of a randomized controlled trials.Ten MRSA isolates,clinically isolated from the Second Xiangya Hospital of Central South University between September and November 2021,were determined the minimum inhibitory concentration(MIC),minimum bactericidal concentration(MBC),and bactericidal kinetic test of lycosin-Ⅰin vitro anti-MRSA by micro-broth dilution method.Additionally,the micro-broth chessboard dilution method was utilized to evaluate the in vitro efficacy of lycosin-Ⅰin combination with eight common antimicrobial agants,including penicillin,erythromycin,levofloxacin,gentamicin,rifampicin,minocycline,vancomycin,and linezolid.Results The MIC range of lycosin-Ⅰagainst MRSA was found to be between 4-8 mg/L with the MIC50 and MIC90 were 4 mg/L and 8 mg/L,respectively.The range of MBC was also between 4-8 mg/L,and the ratio of MBC/MIC was 1-2.The bactericidal kinetics test revealed that the number of surviving MRSA clinical isolates and standard strains initially decreased rapidly but then showed a resurgence when the concentration of lycosin-Ⅰwas 1/2 MIC or MIC.While,the bacterial load gradually reduced until complete elimination when the concentration was at 2 MIC or 4 MIC.The combination of lycosin-Ⅰand gentamicin exhibited mainly synergistic effects,while the combination with other antibiotics showed mainly additive effects.Moreover,the combination of lycosin-Ⅰand antibacterial drugs can significantly reduce the MIC50 and MIC90 of antibiotics.Conclusion lycosin-Ⅰhas great antibacterial and bactericidal activity against MRSA in vitro with rapid and thorough sterilization effect and it can play a synergistic or additive role when combined with other antibacterial drugs against MRSA in vitro.