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. 2010 Dec 6;5(12):e14235.
doi: 10.1371/journal.pone.0014235.

Identification of Brucella by MALDI-TOF mass spectrometry. Fast and reliable identification from agar plates and blood cultures

Laura Ferreira  1 , Silvia Vega Castaño, Fernando Sánchez-Juanes, Sandra González-Cabrero, Fabiola Menegotto, Antonio Orduña-Domingo, José Manuel González-Buitrago, Juan Luis Muñoz-Bellido
Affiliations

Identification of Brucella by MALDI-TOF mass spectrometry. Fast and reliable identification from agar plates and blood cultures

Laura Ferreira et al. PLoS One. .

Abstract

Background: MALDI-TOF mass spectrometry (MS) is a reliable method for bacteria identification. Some databases used for this purpose lack reference profiles for Brucella species, which is still an important pathogen in wide areas around the world. We report the creation of profiles for MALDI-TOF Biotyper 2.0 database (Bruker Daltonics, Germany) and their usefulness for identifying brucellae from culture plates and blood cultures.

Methodology/principal findings: We created MALDI Biotyper 2.0 profiles for type strains belonging to B. melitensis biotypes 1, 2 and 3; B. abortus biotypes 1, 2, 5 and 9; B. suis, B. canis, B ceti and B. pinnipedialis. Then, 131 clinical isolates grown on plate cultures were used in triplicate to check identification. Identification at genus level was always correct, although in most cases the three replicates reported different identification at species level. Simulated blood cultures were performed with type strains belonging to the main human pathogenic species (B. melitensis, B. abortus, B. suis and B. canis), and studied by MALDI-TOF MS in triplicate. Identification at genus level was always correct.

Conclusions/significance: MALDI-TOF MS is reliable for Brucella identification to the genus level from culture plates and directly from blood culture bottles.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. MALDI-TOF MS spectra of whole-cell extracts of Brucella reference strains in the range from 2000 to 11000 Da.
The relative intensity of the ions (a.u., arbitrary units) are shown on the y axis, and the masses (in Da) of the ions are shown on the x axis. The m/z value stands for mass to charge ratio. For a single positive charge, this value corresponds to the molecular weight of the protein.
Figure 2
Figure 2. Cluster analysis of MALDI-TOF MS spectra of Brucella strains and biotypes.
Distance is displayed in relative units.
See this image and copyright information in PMC

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