Identification of Dermatophytosis Agents by Matrix-AssistedLaser Desorption Ionization Time of Flight Mass Spectrometry

Abstract

Objectives: We aimed to evaluate the identification of dermatophytes with Matrix-assisted laser desorption ionizationtime-of-flight mass spectrometry(MALDI-TOF MS). Methods: 138 dermatophytes were identified by applying ethanol-formic acid-acetonitrile extraction protocol tomold subcultures on solid and broth media, using fungal library of MALDI Biotyper(Bruker Daltonics,Germany) system.Scores of ≥1.7 and ≥2.0 were used as identification threshold scores. Morphology-based techniques were used as thediagnostic standard methods. Results: With the threshold score of ≥2.0; 17.6% of 136 isolates extracted from solid media and 59% of 61 isolatesextracted from liquid media could be identified correctly. When the threshold is reduced to 1.7; 61.8% of 136 isolatesextreacted from solid media and all of 61 isolates extracted from liquid media could be identified correctly. Regardlessof the extraction method, 38.4% and 82.6% of the isolates could be identified at the species level when the thresholdscore was accepted as ≥2.0 and ≥1.7, respectively(p