黄绵马酸BB联合红霉素抑制表皮葡萄球菌及其生物被膜的形成研究

目的 探讨黄绵马酸BB与红霉素联用对表皮葡萄球菌(Staphylococcus epidermidis,SE)抑菌活性和生物被膜形成的作用,为黄绵马酸BB开发成为一种新型的生物被膜抑制剂提供理论基础。方法 采用微量稀释法分别测定黄绵马酸BB与红霉素联用对11株SE的最低抑菌浓度(minimum inhibitory concentration,MIC),并采用微量棋盘稀释法测定联合用药的部分抑菌浓度指数(fractional inhibitory concentration index,FICI)与最低抑膜浓度(minimum biofilm inhibitory concentration,MBIC);采用时间-杀菌曲线法,评价联合用药对SE的动态杀菌作用;通过二甲氧唑黄[2.3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[carbonyl(phenylamino)]-2H-tetrazolium hydroxide,XTT]比色法、半定量黏附实验和扫描电子显微镜(scanning electron microscope,SEM)观察,评价联合用药...

Antibacterial and antibiofilm effects of flavaspidic acid BB combined with erythromycin on Staphylococcus epidermidis

Objective To explore the antibacterial and antibiofilm effects of flavaspidic acid BB combined with erythromycin on Staphylococcus epidermidis(SE), and to provide the theoretical basis for the development of flavaspidic acid BB into a new type of antibacterial drug. Methods The microdilution method was used to determine the minimum inhibitory concentration (MIC) of flavaspidic acid BB and erythromycin against 11 strains of SE. And the antimicrobial susceptibility against the strains were evaluated with fractional inhibitory concentration index (FICI) and the minimum biofilm inhibitory concentration (MBIC) of flavaspidic acid BB combined with erythromycin by chessboard dilution method. By drawing a time-kill curve, the dynamic bactericidal effect of flavaspidic acid BB combined and erythromycin on SE was evaluated. XTT colorimetric method, semi-quantitative adhesion test and scanning electron microscope (SEM) were used to evaluate the scavenging effect of the combined drug on the biofilm of the strains. The expression changes of biofilm formation related genes (sarA, aap, agrA) were detected by qRT-PCR. Results FICI value of BB and erythromycin ranged from (0.51 ± 0.00) to (0.75 ± 0.05), which showed additive effect. According to the time-kill curve, the combination of drugs could effectively inhibit and kill the SE. In each stage of biofilm formation, the combination drug group could significantly inhibit the metabolic activity of the tested bacteria and the formation of biofilm substrate quality, and reduce the amount of bacteria and the adhesion between bacteria and inhibit the formation of extracellular polymer. For resistant strain SE04, the expressions ofaap and sarA genes were down-regulated andagrA gene expression was up-regulated at each stage of biofilm formation in drug combination group. For sensitive strain SE08, drug combination group could down-regulate the expression ofaap and sarAgenes at all stages, and up-regulate the expression of agrA gene at adhesion and aggregation stages.Conclusion The combination of flavaspidic acid BB and erythromycin has good antibacterial and antibiofilm effects on SE, which showed additive effect. The antibiofilm effect is associated with inhibiting bacterial metabolic activity, formation of biofilm substrate quality, and the expression of genes related to biofilm formation.