Valero Clara, Buitrago María J, Gago Sara, Quiles-Melero Inmaculada, García-Rodríguez Julio
Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain.
Servicio de Microbiología y Parasitología, Hospital Universitario La Paz, Madrid, Spain.
Med Mycol. 2018 Apr 1;56(3):307-314. doi: 10.1093/mmy/myx047.
The isolation of the pathogenic fungus Histoplasma capsulatum from cultures together with the visualization of typical intracellular yeast in tissues are the gold standard methods for diagnosis of histoplasmosis. However, cultures are time-consuming, require level 3 containment and experienced personnel, and usually call for an additional confirmation test. Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (MALDI-ToF MS) has been established as a suitable tool for microbial identification in several clinical laboratories. A reference database has been constructed for the identification of H. capsulatum by MALDI-ToF MS by using six H. capsulatum strains previously identified by molecular methods. For validation, 63 fungal strains belonging to the Collection of the Spanish National Centre for Microbiology were tested against the new reference database combined with other commercial and in-house databases. In a blind assay, all H. capsulatum strains (n = 30) were correctly identified by the database and 86.6% had scores above 1.7. Considering both phases of the fungus for the same strain, the most reliable results were obtained with the mycelial phase, with only 13.3% of isolates having scores below 1.7. The new database was able to identify both morphological phases of the fungus. MALDI-ToF technology yields a prompt and simple identification from H. capsulatum yeast forms and early mycelial cultures. It allows for reducing response time and decreasing risk in fungus manipulation.
从培养物中分离出致病真菌荚膜组织胞浆菌并在组织中观察到典型的细胞内酵母，是诊断组织胞浆菌病的金标准方法。然而，培养方法耗时，需要三级生物安全防护和经验丰富的人员，并且通常需要额外的确认试验。基质辅助激光解吸电离飞行时间质谱（MALDI-ToF MS）已成为多个临床实验室中用于微生物鉴定的合适工具。通过使用先前通过分子方法鉴定的6株荚膜组织胞浆菌菌株，构建了一个用于通过MALDI-ToF MS鉴定荚膜组织胞浆菌的参考数据库。为了进行验证，对属于西班牙国家微生物学中心菌种保藏库的63株真菌菌株与新的参考数据库以及其他商业和内部数据库进行了比对测试。在一项盲法试验中，数据库正确鉴定了所有30株荚膜组织胞浆菌菌株，86.6%的菌株得分高于1.7。对于同一菌株的两个阶段，在菌丝体阶段获得了最可靠的结果，只有13.3%的分离株得分低于1.7。新数据库能够鉴定该真菌的两个形态阶段。MALDI-ToF技术能够快速、简单地从荚膜组织胞浆菌酵母形态和早期菌丝体培养物中进行鉴定。它可以缩短响应时间并降低真菌操作的风险。
