title: Evaluation of species-specific score cutoff values of routinely isolated clinically relevant bacteria using a direct smear preparation for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry-based bacterial identification.
abstract: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was introduced a few years ago as a new method for bacterial identification. A variety of studies have been published concerning MALDI-TOF MS-based identification, most of them using culture collections for the validation of the respective databases in a retrospective manner in favor of a parallel investigation. The score cutoff value is of special importance for reliable species identification in the Biotyper database. The score cutoff values suggested by the manufacturer have been validated using a previously published formic acid extraction protocol. In most of the previously published studies investigating the Biotyper database, only little information was given concerning species-specific score values. In addition, the mass spectrometer instruments, the number of replicates, the number of spectra used to calculate a sum-spectrum by the supplied software, and the score cutoff values which have been applied varied within these studies. In this study, we compared a straightforward direct smear preparation and measurement without replicate testing to defined biochemical identifications in a parallel manner. In addition, we described new species-specific score cutoff values for the identification of certain bacteria.
authors.affiliation: Institute for Hygiene and Microbiology, Department for Medical Microbiology, University Bochum, National Reference Laboratory for Multidrug-Resistant Gram-Negative Bacteria for Germany, Bochum, Germany. Florian.Szabados@rub.de
authors.forename: F
authors.initials: F
authors.lastname: Szabados
authors.forename: H
authors.initials: H
authors.lastname: Tix
authors.forename: A
authors.initials: A
authors.lastname: Anders
authors.forename: M
authors.initials: M
authors.lastname: Kaase
authors.forename: S G
authors.initials: SG
authors.lastname: Gatermann
authors.forename: G
authors.initials: G
authors.lastname: Geis
mesh_terms: D001419:Bacteria / Q000737:chemistry* / Q000302:isolation & purification*; D001424:Bacterial Infections / Q000175:diagnosis* / Q000382:microbiology*; D001431:Bacteriological Techniques / Q000379:methods*; D006801:Humans; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*