Matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry for fast and accurate identification of clinically relevant Aspergillus species

Abstract

New Aspergillus species have recently been described with the use of multilocus sequencing in refractory cases of invasive aspergillosis. The classical phenotypic identification methods routinely used in clinical laboratories failed to identify them adequately. Some of these Aspergillus species have specific patterns of susceptibility to antifungal agents, and misidentification may lead to inappropriate therapy. We developed a matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS)-based strategy to adequately identify Aspergillus species to the species level. A database including the reference spectra of 28 clinically relevant species from seven Aspergillus sections (five common and 23 unusual species) was engineered. The profiles of young and mature colonies were analysed for each reference strain, and species-specific spectral fingerprints were identified. The performance of the database was then tested on 124 clinical and 16 environmental isolates previously characterized by partial sequencing of the β-tubulin and calmodulin genes. One hundred and thirty-eight isolates of 140 (98.6%) were correctly identified. Two atypical isolates could not be identified, but no isolate was misidentified (specificity: 100%). The database, including species-specific spectral fingerprints of young and mature colonies of the reference strains, allowed identification regardless of the maturity of the clinical isolate. These results indicate that MALDI-TOF MS is a powerful tool for rapid and accurate identification of both common and unusual species of Aspergillus. It can give better results than morphological identification in clinical laboratories.

Identification of Uncommon Clinically Important Yeasts and Moulds by the Bruker Biotyper Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) System in a Global Antifungal Surveillance Program

“…The results of this study both confirm and extend the findings of other investigators who have assured the ability of the Bruker Biotyper to ID clinically relevant yeasts and moulds (Alanio et al, 2011;Buchan and Ledeboer, 2013;Cassagne et al, 2011;Cassagne et al, 2013;Chen et al, 2013;De Carolis et al, 2012). The collection of 80 different species of clinically relevant yet rare yeasts and moulds all IDed by reference DNA sequencing methods presented a rigorous challenge to the Bruker MS system.…”

“…The application of MALDI-TOF MS to the ID of moulds has been more limited to date with the greatest experience having to do with the ID of Aspergillus species (Alanio et al, 2011;Cassagne et al, 2011;De Carolis et al, 2012).…”

Routine Identification of Medical Fungi by the New Vitek MS Matrix-Assisted Laser Desorption Ionization–Time of Flight System with a New Time-Effective Strategy

“…Moreover, the spectrum of identifiable fungal species gradually spreads. While until recently, this technique involved only yeasts, new developments have allowed the use of MALDI-TOF MS for the identification of filamentous fungi, particularly Aspergillus species (1,4).…”

Differentiation of clinically relevant Mucorales Rhizopus microsporus and R. arrhizus by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS)

“…MALDI-TOF MS has primarily been used for identification of bacteria and yeasts, and is increasingly applied in identification of filamentous fungi such as Fusarium, Aspergillus, Penicillium and Ramularia (Alanio et al, 2011;Bader et al, 2011;Hettick et al, 2008;De Carolis et al, 2012;Videira et al, 2015). In the basal lineages of the fungal kingdom, a comprehensive report on MALDI-TOF MS identification of Lichtheimia species has appeared (Schrödl et al, 2012).…”