白假丝酵母菌临床菌株对氟康唑耐药性及其与CAP1基因相关性研究

Resistance of Candida albicans isolates against fluconazole and the resistance correlation with CAP1 gene

目的了解白假丝酵母菌临床菌株对氟康唑的耐药率以及氟康唑耐药与白假丝酵母菌CAP1基因相关性。方法采用微量稀释法检测了245株白假丝酵母菌临床菌株对氟康唑的敏感性。采用实时荧光定量RT-PCR（qRT-PCR）和流式细胞术分别检测白假丝酵母菌CAP1基因mRNA（CAP1-mRNA）及其表达产物Cap1p。采用氟康唑浓度递增（4～64μg/mL）的YPD培养液连续培养法了解氟康唑诱导白假丝酵母菌耐药性的作用,qRT-PCR和流式细胞术确定CAP1基因与氟康唑耐药性形成的关系。结果 134株白假丝酵母菌对氟康唑敏感（MIC≤8μg/mL）、36株剂量依赖敏感（16～32μg/mL）、75株耐药（≥64μg/mL）,耐药率为30.6%（75/245）。氟康唑耐药白假丝酵母菌株CAP1-mRNA和Cap1p表达水平均明显高于氟康唑敏感菌株（P〈0.05）。氟康唑能诱导氟康唑敏感菌株产生耐药性（MIC≥64μg/mL）,其CAP1-mRNA和Cap1p表达水平也显著升高（P〈0.05）。结论白假丝酵母菌临床菌株对氟康唑有较高的耐药率。氟康唑能诱导氟康唑敏感白假丝酵母菌株产生耐药性。白假丝酵母菌对氟康唑耐药性与CAP1基因表达上调密切相关。

The aim of this study is to investigate the resistant rate of Candida albicans （C. albicans） isolates against flucon- azole, and to determine the correlation between the fluconazole-resistance and CAP1 gene of C. albicans. The microdilution test on 245 C. albicans isolates showed that 134 strains were fluconazole-sensitive （MIC≤8μg/mL）, 36 strains were fluconazole- dose-dependent sensitive （16-32 μg/mL） and 75 strains were fluconazole-resistant （≥64 μg/mL） that produced a 30.60% （75/ 245） fluconazole-resistant rate. The real-time fluorescent quantitative RT-PCR （qRT-PCR） and flow cytometric examination confirmed that the mRNA （CAPI-mRNA） and Caplp levels expressed by CAP1 gene in the fluconazole-resistant C. albicans isolates were significantly higher than those in the fluconazole-sensitive isolates （P〈0.05）. When the fluconazole-sensitive C. albicans isolates were continuously cultured in YPD liquid medium containing fluconazole with progressively-increased dosa- ges （4-64 μg/mL）, the isolates produced the resistance against fluconazole （MIC≥64 μg/mL） as well as the CAPI-mRNA and Caplp expression levels were significantly elevated （P〈0.05）. All the data indicate that C. albicans isolates have a higher flu- conazole-resistant rate. Fluconazole can induce the resistance against itself in fluconazole-sensitive C. albicans strains. The flu- conazole-resistance of C. albicans is closely associated with the expression up-regulation of its CAP1 gene.