title: Rapid species diagnosis for invasive candidiasis using mass spectrometry.
abstract: BACKGROUND
  Matrix-assisted laser desorption ionisation time of flight mass spectrometry (MALDI TOF-MS) allows the identification of most bacteria and an increasing number of fungi. The potential for the highest clinical benefit of such methods would be in severe acute infections that require prompt treatment adapted to the infecting species. Our objective was to determine whether yeasts could be identified directly from a positive blood culture, avoiding the 1-3 days subculture step currently required before any therapeutic adjustments can be made.
  
  
  RESULTS
  Using human blood spiked with Candida albicans to simulate blood cultures, we optimized protocols to obtain MALDI TOF-MS fingerprints where signals from blood proteins are reduced. Simulated cultures elaborated using a set of 12 strains belonging to 6 different species were then tested. Quantifiable spectral differences in the 5000-7400 Da mass range allowed to discriminate between these species and to build a reference database. The validation of the method and the statistical approach to spectral analysis were conducted using individual simulated blood cultures of 36 additional strains (six for each species). Correct identification of the species of these strains was obtained.
  
  
  CONCLUSIONS
  Direct MALDI TOF-MS analysis of aliquots from positive blood cultures allowed rapid and accurate identification of the main Candida species, thus obviating the need for sub-culturing on specific media. Subsequent to this proof-of-principle demonstration, the method can be extended to other clinically relevant yeast species, and applied to an adequate number of clinical samples in order to establish its potential to improve antimicrobial management of patients with fungemia.
authors.affiliation: INSERM, U945, Paris, France.
authors.forename: Carine
authors.initials: C
authors.lastname: Marinach-Patrice
authors.forename: Arnaud
authors.initials: A
authors.lastname: Fekkar
authors.forename: Ralitsa
authors.initials: R
authors.lastname: Atanasova
authors.forename: Johanna
authors.initials: J
authors.lastname: Gomes
authors.forename: Laura
authors.initials: L
authors.lastname: Djamdjian
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Brossas
authors.forename: Isabelle
authors.initials: I
authors.lastname: Meyer
authors.forename: Pierre
authors.initials: P
authors.lastname: Buffet
authors.forename: Georges
authors.initials: G
authors.lastname: Snounou
authors.forename: Annick
authors.initials: A
authors.lastname: Datry
authors.forename: Christophe
authors.initials: C
authors.lastname: Hennequin
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Golmard
authors.forename: Dominique
authors.initials: D
authors.lastname: Mazier
mesh_terms: D002177:Candidiasis / Q000175:diagnosis*; D006801:Humans; D040901:Proteomics; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*