临床相关毛孢子菌的鉴定及体外药物敏感性研究

目的探讨临床相关毛孢子菌的鉴定方法及对常见抗真菌药物的体外敏感性。方法对48株临床分离的毛孢子菌分别通过形态学、API20C AUX、Vitek 2 Compact及核糖体rDNA ITS序列分析等方法鉴定到种;采用浓度梯度法（E-test）测定氟康唑、伏立康唑、伊曲康唑、两性霉素B及卡泊芬净对48株毛孢子菌的最低抑菌浓度。结果形态学和API20C AUX、Vitek 2 Compact不能准确区分不同种的毛孢子菌,以核糖体rDNA ITS序列分析将48株毛孢子菌鉴定为8个种：阿萨希毛孢子菌,星型毛孢子菌,皮瘤毛孢子菌,真皮毛孢子菌,皮肤毛孢子菌,赖巴克毛孢子菌,T.domesticum,T.jirovecii。体外药敏结果显示：卡泊芬净对毛孢子菌无体外活性,MIC〉32μg/mL;氟康唑和两性霉素B对毛孢子菌活性差,体外活性最好的药物是伏立康唑和伊曲康唑。结论常规方法不易将毛孢子菌准确鉴定到种的水平,ITS序列分析准确快速,可以辅助临床区分难鉴定毛孢子菌。毛孢子菌药敏谱不同于临床常见其他酵母菌,氟康唑和两性霉素B对其活性差,伏立康唑具有良好的体外抗菌活性。

Identification and in vitro antifungal susceptibility of medically important Trichosporon species

Objective To study the identification method and in vitro antifungal susceptibility of medical Trichosporon spp. Methods Forty-eight Trichosporon strains were identificated by morphology, API 20C AUX, Vitek 2 Compact and rDNA ITS sequencing. MICs of fluconazole, voriconazole, itraconazole, amphotericin B and caspofungin against Trichosporon spp. were detected by E-test method. Results Morphological and biochemical methodologies were unable to differentiate the species of Trichosporon spp. Following the results of ITS-based identification, there were 8 Trichosporon species, including T. asahii, T. asteroids, T. inkin, T. dermatis, T. cutaneum, T. laibaehii, T. domesticum and T. jirovecii. The susceptibihty results revealed that caspofungin had no activity against Trichosporon spp. （ MIC 〉 32 μg/mL）. Amphotericin B and fluconzole had poor antifungal activity towards Trichosporon spp. The most efficient compounds in vitro were voriconazole and itraconazole. Conclusion Identification of Trichosporon spp. by conventional methods is often difficult and inconclusive. ITS-based molecular procedures can provide alternative and more useful methods for characterization and identification of Trichosporon spp. The susceptibility patterns of Trichosporon spp. differ largely to other yeasts. Amphotericin B and fluconazole show poor antifungal activity. Voriconazole and itraconazole seems to be the most effective agents in vitro.