Identification of Uncommon Clinically Important Yeasts and Moulds by the Bruker Biotyper Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) System in a Global Antifungal Surveillance Program

We report the evaluation of the Bruker Biotyper MS (BMS) system for the identification (ID) of 437 isolates of uncommon species of Candida (106 isolates; 17 species), non-Candida yeasts (100 isolates, 16 species), Aspergillus (164 isolates; 11 species) and non-Aspergillus moulds (57 isolates; 36 species) collected from 68 laboratories in 2012.  Using confidence scores of ≥1.7 to <2.0 for genus only ID and scores of ≥2.0 for species-level ID, BMS correctly IDed 89.8% of yeasts and 85.5% of moulds to the genus level and 71.3% and 73.3%, respectively, to the species-level.  Applying a lower threshold of >1.7 for species-level ID to isolates included in the BMS database improved the accuracy of species ID from 88.7% to 99.0% for Candida, from 65.4% to 91.3% for non-Candida yeasts and from 78.6% to 85.4% for moulds.  BMS gave a result of no identification to those species not included in the database and generated very few (5 total, all moulds) mis-IDs, all of which were correctly IDed at the genus-level.