Timely dermatophytes species identification by MALDI-TOF mass spectrometry

International audience ; The conventional identification of dermatophytes requires a long turnaround time and highly skilled mycologists. Matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) is a novel identification tool used for bacteria and yeast identification in the clinical laboratory. We have recently developed a standardized MS-based assay to routinely identify clinical moulds. This study aimed to determine whether the same assay could also identify clinical dermatophytes in the routine laboratory setting. After building a quality controlled reference MS library that included 45 well characterised strains of 14 dermatophytes species, the effects of cycloheximide in the culture medium and incubation time were tested. Then, 134 clinical dermatophyte isolates were prospectively identified using this reference spectra library. MS-based identification was adequate for 131 (97.8%) isolates. Two isolates ( Microsporum canis and Microsporum audouinii ) failed to be identified and one isolate of Microsporum canis was misidentified. Accurate MS-based identification was obtained in 3 days, which dramatically reduced identification turnaround time compared to the classical morphological identification that may take up to 2–3 weeks, in particular when complementary techniques requiring a subculture are performed. It operated similarly well with or without cycloheximide in the culture medium. In conclusion this standardized MALDI-TOF/MS-based identification procedure of filamentous fungi effectively identifies clinical dermatophyte isolates and drastically reduces the response times in the routine clinical laboratory.