The Third Military Medical University (Army Medical University), Chongqing 400038, China.
Department of Dermatology, The Seventh Medical Center of PLA General Hospital (PLA Army General Hospital), Beijing 100700, China.
Med Mycol. 2020 Apr 1;58(3):393-400. doi: 10.1093/mmy/myz088.
Trichosporon asahii infection is difficult to control clinically. This study identified a case with over 15 years of T. asahii infection-related systemic dissemination disease and conducted genome and transcriptome sequencing to identify fluconazole-resistant genes in fluconazole-resistant versus susceptible strains isolated from this patient's facial skin lesions. The data revealed mutations of the ergosterol biosynthetic pathway-related genes in the T. asahii genome of the fluconazole-resistant strain, that is, there were 36 novel mutations of the ERG11 gene, three point mutations (V458L, D457V, and D334S) in the ERG3, and a missense mutation (E349D) in ERG5 in the fluconazole-resistant strain of the T. asahii genome. To ensure that ERG11 is responsible for the fluconazole resistance, we thus simultaneously cultured the strains in vitro and cloned the ERG11 CDS sequences of both fluconazole-susceptible and -resistant strains into the Saccharomyces cerevisiae. These experiments confirmed that these mutations of ERG11 gene affected fluconazole resistance (> 64 μg/ml vs. <8 μg/ml of the MIC value between fluconazole-resistant and -susceptible strains) in Saccharomyces cerevisiae. In addition, expression of ergosterol biosynthesis pathway genes and drug transporter was upregulated in the fluconazole-resistant strain of T. asahii. Collectively, the fluconazole resistance in this female patient was associated with mutations of ERG11, ERG3, and ERG5 and the differential expression of drug transporter and fatty acid metabolic genes.
新生隐球菌感染的临床控制较为困难。本研究报道了 1 例超过 15 年的新生隐球菌感染导致系统性播散疾病的患者，对其面部皮损来源的耐药株和敏感株进行基因组和转录组测序，鉴定了氟康唑耐药基因。结果显示耐药株新生隐球菌基因组中与麦角固醇生物合成途径相关的基因发生了突变，即 ERG11 基因有 36 个新的突变，ERG3 中有 3 个点突变（V458L、D457V 和 D334S），ERG5 中有 1 个错义突变（E349D）。为了确保 ERG11 基因与氟康唑耐药相关，我们在体外同时培养了这 2 株菌，并将氟康唑耐药株和敏感株的 ERG11CDS 序列克隆到酿酒酵母中。这些实验证实 ERG11 基因突变影响了氟康唑耐药性（耐药株和敏感株之间的 MIC 值>64μg/ml vs. <8μg/ml）。此外，新生隐球菌氟康唑耐药株中麦角固醇生物合成途径基因和药物转运蛋白的表达上调。总之，该女性患者的氟康唑耐药与 ERG11、ERG3 和 ERG5 的突变以及药物转运蛋白和脂肪酸代谢基因的差异表达有关。
