The Use of MALDI-TOF Mass Spectrometry to Analyze Commensal Oral Yeasts in Nursing Home Residents

• Published in: Microorganisms Vol. 9; no. 1; p. 142
• Main Authors: Lu, Jang-Jih, Lo, Hsiu-Jung, Lee, Chih-Hua, Chen, Mei-Jun, Lin, Chih-Chao, Chen, Yin-Zhi, Tsai, Ming-Horng, Wang, Shao-Hung
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 09.01.2021; MDPI
• Subjects: Biology (General); Candida; CHROMagar Candida; Color; commensal yeast; Cutaneotrichosporon; Deoxyribonucleic acid; DNA; elderly; Exophiala dermatitidis; Fungi; Gene sequencing; geriatric medicine; Identification methods; Immobilization; Ionization; Ions; Laboratories; MALDI-TOF MS; Mass spectrometry; Mass spectroscopy; matrix-assisted laser desorption-ionization mass spectrometry; Microbiota; Microorganisms; Morphology; Nucleotide sequence; nucleotide sequences; Nursing care; Nursing homes; Older people; oral cavity microorganisms; Oral diseases; Plates; QH301-705.5; Rare species; Ribosomal DNA; Scientific imaging; Spectroscopy; Thermal cycling; Trichosporon; Yeast; yeasts; Germany; commensal yeast; MALDI-TOF MS; CHROMagar Candida; oral cavity microorganisms; geriatric medicine
• ISSN: 2076-2607; 2076-2607
• DOI: 10.3390/microorganisms9010142

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a rapid and accurate method to identify microorganisms in clinical laboratories. This study isolates yeast-like microorganisms in the oral washes that are collected from non-bedridden nursing home residents, using CHROMagar Candida plates, and identifies them using Bruker MALDI-TOF MS. The ribosomal DNA sequences of the isolates are then examined. Three hundred and twenty yeast isolates are isolated from the oral washes. Candida species form the majority (78.1%), followed by Trichosporon/Cutaneotrichosporon species (8.8%). Bruker MALDI-TOF MS gives a high-level confidence, with a log(score) value of ≥1.8, and identifies 96.9% of the isolates. There are six inconclusive results (1.9%), and those sequences are verified as rare clinical species, including Candida ethanolica, Cutaneotrichosporon jirovecii, Exophiala dermatitidis, and Fereydounia khargensis. Almost all of the isolates have a regular color on the CHROMagar Candida plates. If the colonies are grouped by color on the plates, a specific dominant yeast species is present in each color group, except for purple or orange isolates. In conclusion, MALDI-TOF MS is verified as a fast, accurate and practical method to analyze oral yeasts in elderly subjects.