Application Of The Maldi-Tof Ms Technique For Identification Of Dermatophytes

The MALDI-TOF MS method is a new technique, which is being increasingly used in clinical laboratories for identification of microorganisms. The wide interest in this method has been aroused by its high accuracy, instantaneous identification results, and relatively low cost of analyses. However, the application of this technique for identification of dermatophytes poses difficulties. They are caused by the natural biological complexity of filamentous fungi, very slow growth of cultures, and frequent production of pigments. Furthermore, identification of dermatophytes with this technique is a challenge due to the lack of a clear species definition for some taxa or within certain species complexes. A review of scientific literature indicates that the reliability of identification of dermatophytes based on MALDI-TOF MS is in the range between 13.5 and 100%. This variability is determined by many critical factors associated with routine laboratory procedures, i.e. the type of culture medium, incubation time, protein extraction technique, type of device, or version of the reference spectrum library. Despite these numerous limitations, the MALDI-TOF MS method is part of the significant technical progress in mycological diagnostics and an alternative to the time-consuming and labor-intensive identification of dermatophytes based on morphological traits and DNA sequencing. Nevertheless, before the technique can be implemented into routine diagnostic tests, it is necessary to expand the reference spectra library and develop procedures for direct analysis of dermatological samples.

1. Introduction. 2. Identification of microorganisms using the MALDI-TOF MS method. 3. MALDI TOF MS in mycological identification. 4. Critical factors in identification of dermatophytes with the MALDI-TOF method. 4.1. Impact of the microbiological medium. 4.2. Impact of the incubation time. 4.3. Impact of the protein extraction procedure and preparation of the matrix. 4.4. Impact of the mass spectrometry apparatus. 4.5. Impact of the reference spectrum library. 4.6. Impact of the spectrum comparison algorithm. 4.7. Impact of taxonomic changes. 5. Prospects for the development of MALDI-TOF MS in mycological diagnostics. 6. Summary