临床分离白念珠菌 ERG4基因高表达与唑类抗真菌药物耐药的关系

Relationship between ERG4 gene overexpression and azole resistance in clinical Candida albicans strains

目的：探讨临床分离白念珠菌 ERG4基因高表达与唑类抗真菌药物耐药的关系。方法 M27-A2微量肉汤稀释法对34株临床分离白念珠菌菌株进行体外药物敏感性试验。抽提白念珠菌 ERG4基因的总RNA，并逆转录合成 cDNA，采用实时荧光定量 PCR（FQ-RT-PCR）方法检测 ERG4基因 mRNA 表达水平。结果白念珠菌耐氟康唑菌株组 ERG4基因表达量（4.20±2.56）高于敏感组（1.72±1.33）（t =3.99，P 〈0.05）；耐伊曲康唑组（3.60±2.47）高于敏感组（1.66±1.61）（t =3.71，P 〈0.05）；耐伏立康唑组（3.99±2.72）高于敏感组（2.07±1.58）（t =2.91，P 〈0.05）；对氟康唑、伊曲康唑、伏立康唑同时耐药菌株组（4.49±2.73）显著高于敏感组（1.69±1.82）（t =3.81，P 〈0.05）。结论临床分离白念珠菌耐药菌株 ERG4基因高表达与氟康唑、伊曲康唑和伏立康唑耐药及交叉耐药有关，但白念珠菌 ERG4基因高表达在耐药中的作用还有待于通过基因下调进一步研究证实。

Objective To explore the relationship between ERG4 gene overexpression and azole resistance in clinical Candida albicans strains. Methods The National Committee for Clinical Laboratory Standards （NCCLS）M27-A2 broth microdilution method was conducted to evaluate antifungal susceptibility of 34 clinical Candida albicans isolates in vitro. Total RNA was extracted from these Candida albicans strains and transcribed into cDNA. Real-time fluorescence-based quantitative PCR was performed to determine the mRNA expression of ERG4 gene. Statistical analysis was carried out by a two-sample t-test. Results The expression level of ERG4 mRNA was significantly higher in fluconazole-resistant than in -sensitive Candida albicans strains （4.20 ± 2.56 vs. 1.72 ± 1.33, t = 3.99, P 〈 0.05）, higher in itraconazole-resistant than in -sensitive Candida albicans strains （3.60 ± 2.47 vs. 1.66 ± 1.61, t = 3.71, P 〈 0.05）, and higher in voriconazole-resistant than in -sensitive Candida albicans strains （3.99 ± 2.72 vs. 2.07 ± 1.58, t = 2.91, P 〈0.05）. Further more, increased ERG4 mRNA expression was also observed in isolates cross-resistant to all the three azole antifungal agents compared with those susceptible to all of them （4.49 ± 2.73 vs. 1.69 ± 1.82, t = 3.81, P 〈 0.05）. Conclusions The overexpression of ERG4 gene may be associated with cross resistance to fluconazole, itraconazole and voriconazole in clinical Candida albicans strains, but its exact role is expected to be investigated through downregulation of the ERG4 gene.