Wohlmeister Denise, Vianna Débora Renz Barreto, Helfer Virginia Etges, Calil Luciane Noal, Buffon Andréia, Fuentefria Alexandre Meneghello, Corbellini Valeriano Antonio, Pilger Diogo André
Laboratório de Análises Bioquímicas e Citológicas (LABC), Departamento de Análises, Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
Departamento de Análises, Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
J Microbiol Methods. 2017 Oct;141:121-125. doi: 10.1016/j.mimet.2017.08.013. Epub 2017 Aug 16.
Pathogenic Candida species are detected in clinical infections. CHROMagar™ is a phenotypical method used to identify Candida species, although it has limitations, which indicates the need for more sensitive and specific techniques. Infrared Spectroscopy (FT-IR) is an analytical vibrational technique used to identify patterns of metabolic fingerprint of biological matrixes, particularly whole microbial cell systems as Candida sp. in association of classificatory chemometrics algorithms. On the other hand, Soft Independent Modeling by Class Analogy (SIMCA) is one of the typical algorithms still little employed in microbiological classification. This study demonstrates the applicability of the FT-IR-technique by specular reflectance associated with SIMCA to discriminate Candida species isolated from vaginal discharges and grown on CHROMagar™. The differences in spectra of C. albicans, C. glabrata and C. krusei were suitable for use in the discrimination of these species, which was observed by PCA. Then, a SIMCA model was constructed with standard samples of three species and using the spectral region of 1792-1561cm. All samples (n=48) were properly classified based on the chromogenic method using CHROMagar™ Candida. In total, 93.4% (n=45) of the samples were correctly and unambiguously classified (Class I). Two samples of C. albicans were classified correctly, though these could have been C. glabrata (Class II). Also, one C. glabrata sample could have been classified as C. krusei (Class II). Concerning these three samples, one triplicate of each was included in Class II and two in Class I. Therefore, FT-IR associated with SIMCA can be used to identify samples of C. albicans, C. glabrata, and C. krusei grown in CHROMagar™ Candida aiming to improve clinical applications of this technique.
在临床感染中可检测到致病性念珠菌属物种。CHROMagar™是一种用于鉴定念珠菌属物种的表型方法，尽管它有局限性，这表明需要更灵敏和特异的技术。红外光谱（傅里叶变换红外光谱，FT-IR）是一种分析振动技术，用于识别生物基质的代谢指纹图谱模式，特别是作为念珠菌属的整个微生物细胞系统，并结合分类化学计量学算法。另一方面，类模型软独立建模法（SIMCA）是一种在微生物分类中仍很少使用的典型算法。本研究通过与SIMCA相关的镜面反射傅里叶变换红外光谱技术，证明了其在鉴别从阴道分泌物中分离并在CHROMagar™上生长的念珠菌属物种方面的适用性。白色念珠菌、光滑念珠菌和克柔念珠菌光谱的差异适用于这些物种的鉴别，这通过主成分分析（PCA）观察到。然后，用三种物种的标准样品并使用1792 - 1561cm的光谱区域构建了一个SIMCA模型。所有样品（n = 48）根据使用CHROMagar™念珠菌显色方法进行了正确分类。总共93.4%（n = 45）的样品被正确且明确地分类（I类）。两个白色念珠菌样品被正确分类，尽管它们可能是光滑念珠菌（II类）。此外，一个光滑念珠菌样品可能被分类为克柔念珠菌（II类）。关于这三个样品，每个样品的一个重复样品被归入II类，两个被归入I类。因此，与SIMCA相关的傅里叶变换红外光谱可用于鉴定在CHROMagar™念珠菌上生长的白色念珠菌、光滑念珠菌和克柔念珠菌样品，旨在改善该技术的临床应用。
