Veenhuisii毛孢子菌的生物学特性研究

Biological characteristics of Trichosporon veenhuisii

目的探讨自ICU患者的肺泡灌洗液分离到的12株Veenhuisii毛孢子菌的真菌学特征,并对其进行表型鉴定、分子生物学鉴定和抗真菌药物敏感性试验。方法采用患者的肺泡灌洗液标本进行分离培养后,进行常规真菌学鉴定和菌株的ITS区序列测定,以及采用CLSI制定的酵母菌液基稀释法对12株菌株进行体外两性霉素B、氟胞嘧啶、氟康唑、伊曲康唑和伏立康唑5种抗真菌药物敏感性试验。结果 12株毛孢子菌经真菌学表型鉴定为阿萨希毛孢子菌;但ITS区序列测定为Veenhuisii毛孢子菌,体外5种抗真菌药物敏感性试验结果显示,12株Veenhuisii毛孢子菌对两性霉素B、氟胞嘧啶、氟康唑、伊曲康唑和伏立康唑均敏感。结论 Veenhuisii毛孢子菌在人体标本中分离到为我国首次报道,在对其进行的真菌学鉴定中,常规的表型鉴定方法不足以准确鉴定结果,应进行rDNA基因序列检测证实。

OBJECTIVE To explore the mycological characteristics of 12 strains of Trichosporon veenhuisii isolated from alveolar lavage fluid obtained from ICU patients and perform the phenotype identification, molecular biological identification, and drug susceptibility testing of antifungal agents. METHODS The routine mycological identification and sequencing determination of ITS region were performed after the alveolar lavage fluid specimens were isolated and cultured; by means of the yeast liquid-based dilution method specified by CLSI, the in vitro drug susceptibility testing of the 12 strains was performed for five antifungal agents, including amphotericin B, flucytosine, fluconazole, itraconazole, and voriconazole. RESULTS The 12 strains of Trichosporon have been identified as the Trichosporon asahii through mycological phenotype identification but identified as T. veenhuisii by means of the ITS region sequencing. The result of the in vitro drug susceptibility testing for the five antifungal agents indicated that the 12 strains of T. veenhuisii were susceptible to amphotericin B, flucytosine, fluconazole, itraconazole, and voriconazole. CONCLUSION It is reported for the fist time in China that the T. veenhuisii is isolated from the human specimens. As for the mycological identification, the routine phenotype identification method is insufficient to identify accurately, and the rDNA gene sequencing should be performed for verification.