Species identification of dermatophytes isolated in China by matrix-assisted laser desorption ionisation-time-of-flight mass spectrometry

Mycoses. 2020 Dec;63(12):1352-1361. doi: 10.1111/myc.13175. Epub 2020 Sep 17.

Abstract

Background and objectives: Matrix-assisted laser desorption ionisation-time-of-flight mass spectrometry (MALDI-TOF MS) is a novel technique for identifying dermatophytes. This study aimed to detect the limitation of MALDI-TOF MS applied to dermatophytes.

Methods: A total of 113 DNA-sequenced dermatophyte isolates preserved at the Research Center for Medical Mycology of Peking University were selected for this study. Forty-two isolates were selected as reference strains used to create a supplementary database. Seventy-one isolates (Trichophyton rubrum series, T benhamiae series, T mentagrophytes series species and T schoenleinii) were used to evaluate the suitability of the MALDI-TOF MS Biotyper system. MALDI Biotyper 4.0 software was employed to construct the main spectrum profile (MSP) dendrograms.

Results: Correct identification rates at the species and genus levels were 90.1% and 91.5%, respectively, using Bruker Filamentous Fungi Library 1.0 combined with the novel database. The MSP dendrogram of the T rubrum series showed unambiguous separation of T rubrum and T violaceum and that of the T benhamiae series distinguished T verrucosum, T benhamiae and T erinacei. Conversely, the MSP dendrogram of the T mentagrophytes series did not successfully distinguish T mentagrophytes, T interdigitale and T tonsurans.

Conclusion: MALDI-TOF MS showed good performance in the identification and delineation of the T rubrum series and T benhamiae series, but showed poor performance in T mentagrophytes series.

Keywords: dermatomycosis; dermatophytes; identification.

MeSH terms

  • Arthrodermataceae / classification*
  • Arthrodermataceae / isolation & purification
  • China
  • Dermatomycoses / microbiology
  • Humans
  • Mycological Typing Techniques / methods*
  • Phylogeny
  • Sequence Analysis, DNA
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization*