Feng Wenli, Yang Jing, Wang Yiru, Chen Jinyu, Xi Zhiqin, Qiao Zusha
The Department of Dermatovenereology, The Second Hospital of ShanXi Medical University, No. 382, WuYi Road, Taiyuan City, ShanXi Province, 030001 China.
Can J Microbiol. 2016 Nov;62(11):938-943. doi: 10.1139/cjm-2016-0055. Epub 2016 Jul 14.
To better understand the association between the ERG11 gene and drug resistance in Candida krusei, C. krusei strains were isolated from patients from January 2010 to May 2013. Susceptibility to 5-fluorocytosine (5-FC), amphotericin B (AMB), voriconazole (VRC), fluconazole (FLC), and itraconazole (ITR) were tested by broth microdilution method. Mutations were detected using PCR amplification and gene sequencing. Expression levels of ERG11 were measured by real-time PCR and compared by a 2-tailed Student's t test between ITR-susceptible strains and ITR-resistant strains. In total, 15 C. krusei strains were obtained, of which 20.00%, 53.33%, and 40.00% were resistant to 5-FC, FLC, and ITR, respectively, whereas all isolates were susceptible to AMB and VRC. Three synonymous codon substitutions were found in ERG11, including T939C, T642C, and A756T. However, T939C was found in both resistant and susceptible C. krusei strains. The expression level of ERG11 was significantly higher in resistant C. krusei strains (1.34 ± 0.08) than in susceptible C. krusei strains (0.94 ± 0.14) (t = 3.74, p < 0.05). Our study demonstrates that point mutations (T642C and A756T) accompanied with the overexpression of ERG11 might be involved in the molecular mechanisms of drug resistance in C. krusei.
为了更好地了解克鲁斯念珠菌中ERG11基因与耐药性之间的关联，于2010年1月至2013年5月从患者中分离出克鲁斯念珠菌菌株。采用肉汤微量稀释法检测其对5-氟胞嘧啶（5-FC）、两性霉素B（AMB）、伏立康唑（VRC）、氟康唑（FLC）和伊曲康唑（ITR）的敏感性。通过PCR扩增和基因测序检测突变情况。采用实时PCR测定ERG11的表达水平，并通过双尾Student t检验比较ITR敏感菌株和ITR耐药菌株之间的差异。共获得15株克鲁斯念珠菌菌株，其中分别有20.00%、53.33%和40.00%对5-FC、FLC和ITR耐药，而所有分离株对AMB和VRC敏感。在ERG11中发现了三个同义密码子替换，包括T939C、T642C和A756T。然而，在耐药和敏感的克鲁斯念珠菌菌株中均发现了T939C。耐药的克鲁斯念珠菌菌株中ERG11的表达水平（1.34±0.08）显著高于敏感的克鲁斯念珠菌菌株（0.94±0.14）（t=3.74，p<0.05）。我们的研究表明，伴随ERG11过表达的点突变（T642C和A756T）可能参与了克鲁斯念珠菌耐药的分子机制。
