Candida auris has emerged as a multidrug-resistant pathogen of great clinical concern. Approximately 90% of clinical C. auris isolates are resistant to fluconazole, the most commonly prescribed antifungal agent, and yet it remains unknown what mechanisms underpin this fluconazole resistance. To identify novel mechanisms contributing to fluconazole resistance in C. auris, fluconazole-susceptible C. auris clinical isolate AR0387 was passaged in media supplemented with fluconazole to generate derivative strains which had acquired increased fluconazole resistance in vitro. Comparative analyses of comprehensive sterol profiles, [³H]fluconazole uptake, sequencing of C. auris genes homologous to genes known to contribute to fluconazole resistance in other species of Candida, and relative expression levels of C. auris ERG11, CDR1, and MDR1 were performed. All fluconazole-evolved derivative strains were found to have acquired mutations in the zinc-cluster transcription factor-encoding gene TAC1B and to show a corresponding increase in CDR1 expression relative to the parental clinical isolate, AR0387. Mutations in TAC1B were also identified in a set of 304 globally distributed C. auris clinical isolates representing each of the four major clades. Introduction of the most common mutation found among fluconazole-resistant clinical isolates of C. auris into fluconazole-susceptible isolate AR0387 was confirmed to increase fluconazole resistance by 8-fold, and the correction of the same mutation in a fluconazole-resistant isolate, AR0390, decreased fluconazole MIC by 16-fold. Taken together, these data demonstrate that C. auris can rapidly acquire resistance to fluconazole in vitro and that mutations in TAC1B significantly contribute to clinical fluconazole resistance.

中文翻译：

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TAC1B 突变：耳念珠菌临床氟康唑耐药性的新遗传决定因素。


耳念珠菌已成为临床高度关注的多重耐药病原体。大约 90% 的临床耳念珠菌分离株对氟康唑（最常用的抗真菌药物）具有耐药性，但目前尚不清楚这种氟康唑耐药性的机制是什么。为了确定耳念珠菌对氟康唑耐药的新机制，将氟康唑敏感的耳念珠菌临床分离株 AR0387 在补充有氟康唑的培养基中传代，以产生在体外获得更高氟康唑耐药性的衍生菌株。综合甾醇谱、[ ³ H]氟康唑摄取、与已知导致其他念珠菌物种氟康唑耐药性的基因同源的耳念珠菌基因测序以及耳念珠菌ERG11 、 CDR1和MDR1的相对表达水平的比较分析执行。发现所有氟康唑进化的衍生菌株的锌簇转录因子编码基因TAC1B均发生突变，并且相对于亲本临床分离株 AR0387， CDR1表达相应增加。在代表四个主要分支的 304 个全球分布的耳念珠菌临床分离株中也发现了TAC1B突变。介绍在氟康唑耐药临床分离株中发现的最常见突变。 将耳念珠菌引入氟康唑敏感分离株 AR0387 被证实可使氟康唑耐药性增加 8 倍，而纠正氟康唑耐药分离株 AR0390 中的相同突变可使氟康唑 MIC 降低 16 倍。总而言之，这些数据表明耳念珠菌可以在体外快速获得对氟康唑的耐药性，并且TAC1B的突变显着导致临床氟康唑耐药性。