没食子酸联合氟康唑抗耐药非白念珠菌作用的体外试验

The in vitro test on combined antifungal effects of gallic acid and fluconazole against drug resistant non-albicans Candida

目的:研究没食子酸与氟康唑联用对耐药光滑念珠菌和克柔念珠菌的体外抗真菌活性。方法:采用棋盘微量稀释法测定没食子酸与氟康唑单用及联用对耐药光滑念珠菌和克柔念珠菌的抗真菌作用,以部分抑菌浓度指数(FICI)评价其联用效果;并以CG2、CK8为目标菌株,采用时间-杀菌曲线进行验证;通过测定没食子酸对耐药株生物膜形成早期黏附性的影响,初步探讨药物联合抗真菌耐药的作用。结果:联用时8~16μg·m L-1没食子酸能将氟康唑的MIC值降为单用时的1/4~1/8,FICI值为0.375,呈现较好的协同作用,且量效关系呈正相关。时间-杀菌曲线表明,与氟康唑单用相比,没食子酸与氟康唑联用24 h时,CG2、CK8菌株CFU的lg值分别下降了2.1个单位和2.25个单位,均表现为协同作用。另外,研究发现没食子酸对生物膜形成的早期黏附有明显的抑制作用。结论:没食子酸与氟康唑联用对耐药光滑念珠菌和克柔念珠菌的浮游菌表现出体外协同抗真菌作用,且没食子酸能够明显抑制非白色念珠菌生物膜形成的早期黏附。

OBJECTIVE To study the antifungal activity of gallic acid combined with fluconazole against drug resistant Candida glabrata and Candida krusei in vitro. METHODS The antifungal activities of gallic acid combined with fluconazole against drug resistant Candida glabrata and Candida krusei were tested by microplate dilution method. Fractional inhibitory concentration index(FICI) was used to evaluate the effects of drug combination. Time-kill curves were used to validate the trial results with CK8 and CG2 as target strains. The effects of combined antifungal drug resistance were preliminarily discussed through determining the effect of gallic acid on the adhesion of drug resistant strains at the early stage of biofilm formation. RESULTS When used in combination,gallic acid in dose range of 8-16 μg·m L-1 could reduce the MIC value of fluconazole to 1/4-1/8 compared with the value alone. FICI value was 0. 375,presenting a preferable synergistic effect. The concentration response relationship was positively correlated. The timekill assay test results confirmed the synergy when fluconazole was used in combination with gallic acid and the log10 CFU·m L-1 was decreased by 2. 1 and 2. 25 at 24 h compared with fluconazole used alone,respectively. Furthermore,the research also proved that gallic acid had the obvious inhibitory action on early adhesion during biofilm formation against Candida glabrata and Candida krusei resistant to fluconazole. CONCLUSION Gallic acid combined with fluconazole show synergistic effects to fluconazole resistant Candida glabrata and Candida krusei. Gallic acid has obvious inhibitory effects on early adhesion during biofilm formation against fluconazole resistant nonalbicans Candida.