Evaluation of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry to differentiate Candida

Abstract

Objective To evaluate the efficiency of matrix assisted laser analytical ionization time of flight mass spectrometry (MALDI-TOF-MS) for identification of Candida species which caused vulvovaginal candidiasis(VVC). Methods Candida strains from VVC were first identified by PCR amplification of the ITS regions and transposable intron of DNA and sequencing analysis. MALDI-TOF-MS wasfurther performed to identify the strainsconfirmedby molecular methods, and at the same time the MALDI-TOF-MS identification database of C. albicans complex was set up. Results In total, 324 Candida strains were identifiedby molecular methods from VVC samples, which encompassed20 different yeast species, including C. albicans, C. africana, C. dubliniesis, C. glabrata, C. bracarensis, C. nivariensis, C. guilliermondii, C. lusitaniae, C. krusei, C. kefyr, C. parapsilosis, C. metapsilosis, C. tropicalis, Kodamaea ohmeri, C. fabianii, Rhodotorula mucilaginosa, Saccharomyces cerevisiae, and Trichosporon asahii.314of all 324 Candida strains were correctly identified by MALDI-TOF-MS. 3 C. albicans, 1 C. africana, 1 C. glabrata, 2 C. metapsilosis, 1 C. guilliermondii and 1 Saccharomyces cerevisiae were incorrectly identified, while 1 Torulaspora pretoriensiscannot identified. The accuracy ofidentification was 96.91 % (314/324). 97.95%(191/195 )of Candida strains, including 153 (98.08%)C. albicans, 37 (97.37%) C. africanaand 1(100%) C. dubliniesis, can be correctly identifiedby the newbuiltC. albicans complex database. Conclusion MALDI-TOF-MS is proved to be a rapid and reliable method for identification of Candida strains from VVC, which also has advantages of identification of Candida complex.(Chin J Lab Med, 2018, 41: 296-299) Key words: Candidiasis, vulvovaginal; Candida; Spectrometry, mass, matrix-assisted laser desorption-ionization