光滑念珠菌临床分离株对氟康唑耐药的分子机制

Molecular mechanisms of fluconazole resistance in clinical isolates of Candida glabrata

目的明确光滑念珠菌临床分离株对氟康唑耐药的主要分子机制。方法采用实时荧光定量RT—PCR技术对光滑念珠菌临床分离株ERG11、CDR1和CDR2基因表达的mRNA进行相对定量，比较氟康唑耐药株与敏感株基因表达水平的差异。结果在光滑念珠菌氟康唑耐药株、剂量依赖性敏感株及敏感株中，ERG11基因mRNA相对表达量分别为：121．4±96．8、102．9±78．8、51．2±20．7；CDR1基因mRNA相对表达量分别为：3．1±1．4、1．9±0．7、1．1±0．4；CDR2基因mRNA相对表达量分别为：3．7±2．2、3．4．4-2．4、1．9±0．9。耐药株ERG11基因mRNA表达量高于敏感株（P=0．041）；耐药株（P〈0．001）和剂量依赖性敏感株（P=0．009）CDRl基因mRNA表达量均高于敏感株；耐药株CDR2基因mRNA表达量高于敏感株（P=0．018）。随着光滑念珠菌对氟康唑敏感性的降低，ERG11、CDR1及CDR2基因mRNA的表达量均不同程度上升。结论ERG11、CDR1及CDR2基因mRNA的上调表达与光滑念珠菌临床分离株对氟康唑的耐药性有关，ERG11、CDR1及CDR2基因上调表达是光滑念珠菌临床分离株对氟康唑耐药的主要分子机制。

Objective To determine if changes in the levels of expression of ERGll, CDR1 and CDR2 genes could be associated with resistance phenotype in clinical isolates of Candida glabrata （ C. glabrata）. Methods We used quantitative RT-PCR analysis to evaluate the expression of the ERG11, CDR1 and CDR2 genes in clinical isolates including 9 flueonazole-resistant, 9 flueonazole-susceptible dose dependent（S-DD） and 10 fluconazole-sensitive C. glabrata isolates. Results In the fluconazole-resistant isolates,the S-DD isolates and the fluconazole-sensitive isolates, the levels of expression of ERG11 gene were 121.4 ±96. 8, 102. 9 ±78. 8, 51.2 ±20. 7, respectively; the levels of expression of CDR1 gene were 3.1 ± 1.4,1.9 ± 0. 7,1.1 ± 0. 4, respective!y; the levels of expression of CDR2 gene were 3.7 ± 2. 2,3.4 ± 2.4, 1.9 ± 0. 9, respectively. Quantitative RT-PCR analyses revealed that the fluconazole-resistant isolates expressed ERGll at higher levels than fluconazole-sensitive isolates （P = 0. 041 ）. CDR1 expression was significantly higher in the fluconazole-resistant isolates as compared with that in the fluconazole-sensitive isolates（ P 〈0. 001 ）and the expression was also significantly higher in the S-DD isolates as compared with that in the fluconazole-sensitive isolates （P = 0. 009）. CDR2 upregnlation was observed in the fluconazoleresistant isolates as compared with the susceptible isolates（P =0. 018）. With the decrease of susceptibility to fluconazole, the levels of expression of ERG11, CDR1 and CDR2 genes in the isolates appeared to be increased. Conclusions These results provide evidence that the overexpression of ERGll, CDR1 and CDR2 genes is associated with the increase of fluconazole resistance in clinical isolates of C. glabrata. ERG11, CDR1 and CDR2 upregulation is a major molecular mechanism of flueonazole resistance in clinical isolates of C. glabrata.