identification of clinical dermatophyte isolates obtained from iran by matrix-assisted laser desorption/ionization time-off-light mass spectrometry

Background and purpose: matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (maldi-tof ms) is widely used to discriminate among pathogenic microorganisms in clinical laboratories. the aim of this study was to assess the utility of maldi-tof ms in the routine identification of clinical dermatophyte isolates obtained from various geographical regions of iran. materials and methods: a total of 94 isolates, including trichophyton interdigitale (n=44), t. rubrum (n=40), t. tonsurans (n=4), microsporum canis (n=4), and epidermophyton floccosum (n=1), were analyzed in this study. the identity of each isolate was determined by polymerase chani reaction amplification and sequencing of the internal transcribed spacer (its) region of nuclear-encoded ribosomal dna and also maldi-tof ms. the obtained data by molecular approach were compared with maldi-tof ms. results: the maldi-tof ms led to the identification of 44 (47%) isolates at the species level by generating the spectral score values of ≥ 2.0. however, there was not sufficient agreement between the results of the molecular-based its identification methods and maldi-tof ms in the species identification of 16 (17%) isolates. the bruker daltonics database was also not able to identify protein spectra related to 12 isolates (13%), including t. interdigitale (n=5), t. rubrum (n=4), m. canis (n=2), and t. tonsurans (n=1). conclusion: according to the results, the utility of maldi-tof ms as a routine diagnostic tool for the accurate and reliable identification of dermatophytes can be justified whenever the protein spectra of a large set of worldwide clinical isolates are included in the commercial libraries. in addition, maldi-tof ms can be alternatively used to construct an in-house reference database.