Multicenter evaluation of three different MALDI-TOF MS systems for identification of clinically relevant filamentous fungi

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) holds promise as a potential tool for clinical identification of filamentous fungi. However, due to the lack of an appropriate extraction protocol and the difficulty of database building, the identification power of each system differs. In this study, we selected 126 clinical mould isolates comprising 28 species identified using internal transcribed spacer (ITS) sequencing as the reference method to evaluate three MALDI-TOF MS systems. When using cultures and sample preparation as recommended by the respective vendors, of the 126 strains tested, VITEK MS identified 121 (96.0%) to species-level and 124 (98.4%) to genus-level; Biotyper identified 53 (42.1%) to species-level and 54 (42.9%) to genus-level; Autof identified 74 (58.7%) to species-level and 76 (60.3%) to genus-level. For the Autof system, the tube extraction method recommended by the vendor performed better (59%) than the on-plate lysis (51%). Our study demonstrates that MALDI-TOF MS systems can successfully identify most clinically relevant fungi, while performance is still highly dependent on the database and sample preparation protocol.