title: Assessment of various parameters to improve MALDI-TOF MS reference spectra libraries constructed for the routine identification of filamentous fungi.
abstract: BACKGROUND
  The poor reproducibility of matrix-assisted desorption/ionization time-of-flight (MALDI-TOF) spectra limits the effectiveness of the MALDI-TOF MS-based identification of filamentous fungi with highly heterogeneous phenotypes in routine clinical laboratories. This study aimed to enhance the MALDI-TOF MS-based identification of filamentous fungi by assessing several architectures of reference spectrum libraries.
  
  
  RESULTS
  We established reference spectrum libraries that included 30 filamentous fungus species with various architectures characterized by distinct combinations of the following: i) technical replicates, i.e., the number of analyzed deposits for each culture used to build a reference meta-spectrum (RMS); ii) biological replicates, i.e., the number of RMS derived from the distinct subculture of each strain; and iii) the number of distinct strains of a given species. We then compared the effectiveness of each library in the identification of 200 prospectively collected clinical isolates, including 38 species in 28 genera.Identification effectiveness was improved by increasing the number of both RMS per strain (p<10-4) and strains for a given species (p<10-4) in a multivariate analysis.
  
  
  CONCLUSIONS
  Addressing the heterogeneity of MALDI-TOF spectra derived from filamentous fungi by increasing the number of RMS obtained from distinct subcultures of strains included in the reference spectra library markedly improved the effectiveness of the MALDI-TOF MS-based identification of clinical filamentous fungi.
authors.affiliation: AP-HM, Parasitologie-Mycologie, CHU Timone, 13005 Marseille, France. anne-cecile.normand@ap-hm.fr
authors.forename: Anne-Cécile
authors.initials: AC
authors.lastname: Normand
authors.forename: Carole
authors.initials: C
authors.lastname: Cassagne
authors.forename: Stéphane
authors.initials: S
authors.lastname: Ranque
authors.forename: Coralie
authors.initials: C
authors.lastname: L'ollivier
authors.forename: Patrick
authors.initials: P
authors.lastname: Fourquet
authors.forename: Sam
authors.initials: S
authors.lastname: Roesems
authors.forename: Marijke
authors.initials: M
authors.lastname: Hendrickx
authors.forename: Renaud
authors.initials: R
authors.lastname: Piarroux
mesh_terms: D005658:Fungi / Q000737:chemistry* / Q000145:classification*; D006801:Humans; D008828:Microbiological Techniques / Q000379:methods*; D009172:Mycology / Q000379:methods*; D009181:Mycoses / Q000175:diagnosis / Q000382:microbiology; D015203:Reproducibility of Results; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
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