Silva Laura N, Ramos Lívia S, Oliveira Simone S C, Magalhães Lucas B, Cypriano Jefferson, Abreu Fernanda, Macedo Alexandre J, Branquinha Marta H, Santos André L S
Laboratório de Estudos Avançados de Microrganismos Emergentes e Resistentes (LEAMER), Instituto de Microbiologia Paulo de Góes (IMPG), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro 21941-902, Brazil.
Laboratório de Biologia Celular e Magnetotaxia & Unidade de Microscopia Multiusuário, Instituto de Microbiologia Paulo de Góes (IMPG), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro 21941-902, Brazil.
J Fungi (Basel). 2023 Aug 18;9(8):859. doi: 10.3390/jof9080859.
Echinocandins, used for the prevention and treatment of invasive fungal infections, have led to a rise in breakthrough infections caused by resistant species. Among these species, those belonging to the complex are rare multidrug-resistant (MDR) yeasts that are frequently misidentified but have emerged as significant healthcare-associated pathogens causing invasive infections. The objectives of this study were to investigate the evolutionary pathways of echinocandin resistance in by identifying mutations in the gene and evaluating the impact of resistance on fitness. After subjecting a MDR clinical isolate of (named Ch4) to direct selection using increasing caspofungin concentrations, we successfully obtained an isolate (designated ) that exhibited a high level of resistance, with MIC values exceeding 16 mg/L for all tested echinocandin drugs (caspofungin, micafungin, and anidulafungin). Sequence analysis revealed a specific mutation in the resistant strain, leading to an arginine-histidine amino acid substitution (R1354H), occurring at the G4061A position of the HS2 region of the gene. Compared to the wild-type strain, exhibited significantly reduced growth proliferation, biofilm formation capability, and phagocytosis ratio, indicating a decrease in fitness. Transmission electron microscopy analysis revealed alterations in cell wall components, with a notable increase in cell wall thickness. The resistant strain also exhibited higher amounts (2.5-fold) of chitin, a cell wall-located molecule, compared to the wild-type strain. Furthermore, the resistant strain demonstrated attenuated virulence in the larval model. The evolved strain maintained its resistance profile in vivo since the treatment with either caspofungin or micafungin did not improve larval survival or reduce the fungal load. Taken together, our findings suggest that the acquisition of pan-echinocandin resistance occurred rapidly after drug exposure and was associated with a significant fitness cost in . This is particularly concerning as echinocandins are often the first-line treatment option for MDR species.
棘白菌素用于预防和治疗侵袭性真菌感染，导致了由耐药菌株引起的突破性感染的增加。在这些菌株中，属于该复合体的那些是罕见的多重耐药（MDR）酵母，它们经常被错误鉴定，但已成为引起侵袭性感染的重要医疗相关病原体。本研究的目的是通过鉴定 基因中的突变并评估耐药性对适应性的影响，来研究棘白菌素耐药性的进化途径。在用逐渐增加的卡泊芬净浓度对一株MDR临床分离株（命名为Ch4）进行直接筛选后，我们成功获得了一株分离株（命名为 ），该分离株表现出高水平的耐药性，所有测试的棘白菌素药物（卡泊芬净、米卡芬净和阿尼芬净）的MIC值均超过16 mg/L。序列分析显示耐药 菌株中有一个特定突变，导致精氨酸 - 组氨酸氨基酸取代（R1354H），发生在 基因HS2区域的G4061A位置。与野生型菌株相比， 表现出显著降低的生长增殖、生物膜形成能力和吞噬率，表明适应性下降。透射电子显微镜分析显示细胞壁成分发生改变，细胞壁厚度显著增加。与野生型菌株相比，耐药菌株还表现出更高含量（2.5倍）的几丁质，一种位于细胞壁的分子。此外，耐药菌株在 幼虫模型中表现出减弱的毒力。由于用卡泊芬净或米卡芬净治疗均未提高幼虫存活率或降低真菌负荷，进化后的菌株 在体内保持了其耐药谱。综上所述，我们的研究结果表明，在药物暴露后，泛棘白菌素耐药性的获得迅速发生，并且与 中的显著适应性代价相关。鉴于棘白菌素通常是MDR 菌株的一线治疗选择，这尤其令人担忧。
