微量稀释法检测申克孢子丝菌酵母相体外抗真菌药物敏感性

目的用液基微量稀释法观察双相真菌申克孢子丝菌酵母相体外抗真菌药物敏感性。方法将54株申克孢子丝菌临床株于脑心浸液琼脂培养基连续传代获得酵母相,参考美国临床实验室标准化委员会(CLSI)的微量稀释法M27-A2检测菌株酵母相对碘化钾、氟康唑、伊曲康唑和特比萘芬的体外敏感性,并观察碘化钾对伊曲康唑和特比萘芬体外抑菌作用的影响。质控株为克柔念珠菌ATCC6258。结果碘化钾体外无抑菌作用;氟康唑最小抑菌浓度(MIC)几何均数大于64μg/mL;伊曲康唑和特比萘芬MIC几何均数分别为0.98μg/mL和0.17μg/mL。伊曲康唑及特比萘芬的MIC值分别高于伊曲康唑+碘化钾及特比萘芬+碘化钾(P均<0.05)。来源皮肤固定型的菌株与来源皮肤淋巴管型菌株相比MIC值差异无统计学意义(P>0.05)。结论改良的M27-A2方法适用于检测申克孢子丝菌酵母相体外敏感性;酵母相时碘化钾对伊曲康唑、特比萘芬体外抑菌作用有一定的加强效应。

In Vitro Antifungal Susceptibility of Yeast Phase of Sporothrix schenckii by Microdilution Broth Method

Objective To evaluate the activities of potassium iodide,fluconazole,itraconazole,terbinafine on yeast phase of Sporothrix shenckii,and investigate the effect of potassium iodide on itraconazole and terbinafine by microdilution broth method in vitro.Methods Fifty-four isolates of Sporothrix shenckii were converted to the yeast form successive passages on Brain Heart Infusion Agar medium at 35℃.Then according to a modified CLSI microdilution method M27-A2,tested the susceptibility of these isolates to potassium iodide,fluconazole,itraconazole,terbinafine.We added potassium iodide in RPMI-1640,then compared the susceptibility of itraconazole and terbinafine with the former in vitro.Candida krusei ATCC 6258 was used for quality control.Results Potassium iodide showed no antifungal activity in vitro.Terbinafine had the best susceptibility,with geometric mean of 0.17μg/mL,MIC range is 0.03～1μg/mL.The MIC of itraconazole is 0.03～8μg/mL(0.98μg/mL).Fluconazole has a high MIC(>64μg/mL).With potassium iodide in RPMI-1640,the MICs of terbinafine and itraconazole were significantly different from the former results(P<0.05).But there were no significant difference in MIC between isolates from cutaneous sporotrichosis and lymphocutaneous sporotrichosis(P>0.05).Conclusion A modified M27-A2 is an alternative method for testing yeast phase of Sporothrix schenckii.Potassium iodide can improve the antifungal susceptibility of terbinafine and itraconazole to yeast phase in vitro.