BackgroundMeyerozyma guilliermondii is a yeast species responsible for invasive fungal infections. It has high minimum inhibitory concentrations (MICs) to echinocandins, the first‐line treatment of candidemia. In this context, azole antifungal agents are frequently used. However, in recent years, a number of azole‐resistant strains have been described. Their mechanisms of resistance are currently poorly studied.ObjectiveThe aim of this study was consequently to understand the mechanisms of azole resistance in several clinical isolates of M. guilliermondii.MethodsTen isolates of M. guilliermondii and the ATCC 6260 reference strain were studied. MICs of azoles were determined first. Whole genome sequencing of the isolates was then carried out and the mutations identified in ERG11 were expressed in a CTG clade yeast model (C. lusitaniae). RNA expression of ERG11, MDR1 and CDR1 was evaluated by quantitative PCR. A phylogenic analysis was developed and performed on M. guilliermondii isolates. Lastly, in vitro experiments on fitness cost and virulence were carried out.ResultsOf the ten isolates tested, three showed pan‐azole resistance. A combination of F126L and L505F mutations in Erg11 was highlighted in these three isolates. Interestingly, a combination of these two mutations was necessary to confer azole resistance. An overexpression of the Cdr1 efflux pump was also evidenced in one strain. Moreover, the three pan‐azole‐resistant isolates were shown to be genetically related and not associated with a fitness cost or a lower virulence, suggesting a possible clonal transmission.ConclusionIn conclusion, this study identified an original combination of ERG11 mutations responsible for pan‐azole‐resistance in M. guilliermondii. Moreover, we proposed a new MLST analysis for M. guilliermondii that identified possible clonal transmission of pan‐azole‐resistant strains. Future studies are needed to investigate the distribution of this clone in hospital environment and should lead to the reconsideration of the treatment for this species.

中文翻译：

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Erg11 中具有 F126L 和 L505F 双突变的泛唑抗性吉里蒙菌克隆分离株

背景吉里蒙粗酶是一种导致侵袭性真菌感染的酵母菌种。它对念珠菌血症的一线治疗药物棘白菌素具有较高的最低抑制浓度 (MIC)。在这种情况下，经常使用唑类抗真菌剂。然而，近年来，已经描述了许多唑类抗性菌株。目前对其耐药机制的研究还很少。 目的本研究的目的是了解几种临床分离菌株对唑类药物的耐药机制。吉利蒙氏菌.方法十个分离株吉利蒙氏菌和 ATCC 6260 参考菌株进行了研究。首先测定唑类的 MIC。然后对分离株进行全基因组测序，并鉴定出突变ERG11在 CTG 分支酵母模型中表达（卢西塔尼亚克.）。RNA 表达ERG11、多药耐药1和互补决定区1通过定量PCR进行评估。开发并进行了系统发育分析吉利蒙氏菌隔离。最后，进行了适应度成本和毒力的体外实验。结果在测试的10个分离株中，3个显示出泛唑耐药性。在这三个分离株中，突出显示了 Erg11 中 F126L 和 L505F 突变的组合。有趣的是，这两种突变的组合对于赋予唑类耐药性是必要的。在一种菌株中也证实了 Cdr1 外排泵的过度表达。此外，这三种全唑抗性分离株被证明具有遗传相关性，并且与适应度成本或较低毒力无关，表明可能存在克隆传播。 结论 总之，本研究确定了一种原始组合ERG11导致泛唑耐药的突变吉利蒙氏菌。此外，我们提出了一种新的 MLST 分析吉利蒙氏菌确定了泛唑耐药菌株可能的克隆传播。未来的研究需要调查该克隆在医院环境中的分布，并应导致重新考虑对该物种的治疗。