Matrix-Assisted Laser Desorption/Ionization Time-of-flight Mass spectrometry (MALDI-TOF) is a reliable tool for the identification of bacteria and yeasts. A number of publications have detailed methods for the analysis of filamentous fungi however there are few publications incorporating the use into routine mycology laboratories which do not involve creating a reference spectral library.
In this study, the performance of the Bruker Microflex LT biotyper system (BrukerDaltonics Bremen Germany) for the identification of yeasts and moulds was compared to traditional mycology methods and ITS sequencing by utilising the commercial Bruker database Bruker Filamentous Fungi Library (version 3.1).
A total of 258 isolates of yeast were analysed by either a direct smear formic acid-extraction or by an extended formic acid extraction. The yeasts were isolates from a variety of clinical specimens including blood cultures and sterile sites. 200 isolates of filamentous fungi isolated from clinical specimens were analysed using the Bruker recommended broth method. These included isolates of Aspergillus, Scedosporium, Trichophyton and Microsporum.
In summary, the MALDI-TOF method provides an inexpensive, standardized working protocol for the rapid identification of many clinically relevant yeast and mould isolates which can dramatically improve turn-around time for mycology specimens. The techniques are reliable for many of the common clinically isolated yeasts and some of the moulds isolated from clinical specimens. The methods have been incorporated into our routine mycology laboratory without the need to create a reference spectral library.