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.
Eur J Clin Microbiol Infect Dis 2011;
31:1109-19. [PMID:
21948378 DOI:
10.1007/s10096-011-1415-7]
[Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Accepted: 08/31/2011] [Indexed: 12/17/2022]
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.
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