Validation of a New Web Application for Identification of Fungi by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

Abstract

Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry has emerged as a reliable technique to identify molds involved in human diseases, including dermatophytes, provided that exhaustive reference databases are available. This study assessed an online identification application based on original algorithms and an extensive in-house reference database comprising 11,851 spectra (938 fungal species and 246 fungal genera). Validation criteria were established using an initial panel of 422 molds, including dermatophytes, previously identified via DNA sequencing (126 species). The application was further assessed using a separate panel of 501 cultured clinical isolates (88 mold taxa including dermatophytes) derived from five hospital laboratories. A total of 438 (87.35%) isolates were correctly identified at the species level, while 26 (5.22%) were assigned to the correct genus but the wrong species and 37 (7.43%) were not identified, since the defined threshold of 20 was not reached. The use of the Bruker Daltonics database included in the MALDI Biotyper software resulted in a much higher rate of unidentified isolates (39.76 and 74.30% using the score thresholds 1.7 and 2.0, respectively). Moreover, the identification delay of the online application remained compatible with real-time online queries (0.15 s per spectrum), and the application was faster than identifications using the MALDI Biotyper software. This is the first study to assess an online identification system based on MALDI-TOF spectrum analysis. We have successfully applied this approach to identify molds, including dermatophytes, for which diversity is insufficiently represented in commercial databases. This free-access application is available to medical mycologists to improve fungal identification.

Substandard and falsified antimicrobials: A potential biohazard in disguise?

“…18,19 Identification of the encountered bacteria was performed according to the procedure utilized by Janvier et al 13 18,19 Identification of the encountered bacteria was performed according to the procedure utilized by Janvier et al 13 …”

“…When fungi were detected in the samples, they were analyzed by a validated matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) system, coupled to MALDI Biotyper 3 software (Bruker Daltonics, Bremen, Germany) containing both commercially available spectra and in-house generated spectra. 18,19 Identification of the encountered bacteria was performed according to the procedure utilized by Janvier et al 13…”

Avaliação da metodologia de espectrometria de massas MALDI-TOF (VITEK MS®) para identificação de espécies de Aspergillus de importância médica

“…A diferença entre os protocolos utilizados está no método de coleta das estruturas fúngicas, seja com swab umedecido, como recomendado pela bioMérieux, ou através da coleta de material com bisturi (Lau et al, 2013;Normand et al, 2017) O aparelho de EM MALDI-TOF VITEK MS ® e sua biblioteca de ER IVD (versão 3.0) foi recentemente aprovado pelo U.S. Food and Drug Administration (FDA) para identificação de fungos filamentosos (Rychert et al, 2018), e dois recentes estudos mostraram desempenho de 86-93% de identificações corretas de espécies do gênero…”

“…Aspergillus (McMullen et al, 2016;Rychert et al, 2018), performance similar à apresentada neste estudo. Em comparação a análises prévias realizadas com o equipamento da Bruker e sua biblioteca IVD (Bruker Daltonics, Alemanha), o sistema VITEK MS ® , aprovado para uso clínico, apresenta melhor performance para identificação de espécies de Aspergillus (Lau et al, 2013, Normand et al, 2017 tamari, não teve identificação de gênero e espécie pela biblioteca IVD.…”

“…A maior biblioteca de ER para fungos filamentosos foi construída pelo grupo francês chefiado pelo já mencionado Professor Renaud Piarroux. Tal biblioteca contém 11.851 espectros de 938 espécies, incluindo espécies crípticas de Aspergillus (Normand et al, 2017). De maneira pioneira, a biblioteca está disponível online (MSI web) e usuários dos equipamentos da Bruker podem ter acesso e analisar remotamente espectros de massa, e submetê-los para identificação (Normand et al, 2017) et al, 2016).…”