Medical Mycology Unit, Department of Microbiology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India.
Department of Zoology, Ramjas College, University of Delhi, Delhi, India.
Methods Mol Biol. 2022;2517:3-20. doi: 10.1007/978-1-0716-2417-3_1.
Candida auris is a multidrug-resistant yeast causing healthcare-associated outbreaks of blood stream infections worldwide. Currently, C. auris isolation and identification is complicated by issues such as misidentification and long turnaround time associated with application of commonly used diagnostic tools. Based on phenotypic characteristics, differentiation of C. auris from related Candida haemulonii complex spp. is problematic. Candida auris can be misidentified using biochemical-based systems such as VITEK 2 YST, API 20C, BD Phoenix yeast identification system, and MicroScan. C. auris growth at 42 °C and in the presence of 10% NaCl helps in presumptive identification of this yeast from related Candida haemulonii complex spp. A new CHROMagar™ Candida Plus agar is an excellent alternative to current conventional mycological media for the screening of patients colonized/infected with Candida auris. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) can differentiate C. auris from other Candida species, but not all the reference databases included in MALDI-TOF devices allow for detection. Currently, accurate identification of C. auris can be performed using the updated FDA-approved libraries or "research use-only" libraries. Molecular techniques have greatly enhanced the diagnosis of C. auris. Sequencing of rDNA genetic loci, namely, internal transcribed spacer and D1/D2 region of large subunit (LSU), and PCR/qPCR assays has successfully been applied for identification of C. auris. Real-time PCR assays bear incomparable potential of being the most efficient tool for high-throughput screening of surveillance samples. If properly validated, they can deliver the diagnostic result within several hours, since the DNA can be isolated directly from the patient specimen without the need of obtaining a colony. In this chapter we detailed the isolation of Candida auris from various clinical specimens and its currently available identification methods and hitches.
耳念珠菌是一种多重耐药的酵母，可导致全球范围内与医疗保健相关的血流感染暴发。目前，由于常用诊断工具的应用存在鉴定错误和周转时间长等问题，耳念珠菌的分离和鉴定变得复杂。根据表型特征，从相关的半乳聚糖念珠菌复合体 spp. 中区分耳念珠菌存在问题。使用基于生化的系统，如 VITEK 2 YST、API 20C、BD Phoenix 酵母鉴定系统和 MicroScan，可能会错误鉴定耳念珠菌。耳念珠菌在 42°C 和 10%NaCl 的存在下生长有助于从相关的半乳聚糖念珠菌复合体 spp. 中推定鉴定这种酵母。一种新的 CHROMagar™ Candida Plus 琼脂是目前常规真菌学培养基的极好替代品，可用于筛选定植/感染耳念珠菌的患者。基质辅助激光解吸/电离飞行时间 (MALDI-TOF) 可将耳念珠菌与其他念珠菌种区分开来，但并非 MALDI-TOF 设备中包含的所有参考数据库都允许检测。目前，使用更新的 FDA 批准的库或“仅供研究使用”的库可以准确鉴定耳念珠菌。分子技术极大地增强了耳念珠菌的诊断。rDNA 遗传基因座，即内部转录间隔区和大亚基 (LSU) 的 D1/D2 区的测序以及 PCR/qPCR 检测已成功用于鉴定耳念珠菌。实时 PCR 检测具有无与伦比的潜力，是用于高通量筛选监测样本的最有效工具。如果经过适当验证，它们可以在数小时内提供诊断结果，因为可以直接从患者标本中分离 DNA，而无需获得菌落。在本章中，我们详细介绍了从各种临床标本中分离耳念珠菌及其目前可用的鉴定方法和障碍。
