Rapid identification of Burkholderia cepacia complex species including strains of the novel Taxon K, recovered from cystic fibrosis patients by intact cell MALDI-ToF mass spectrometry

Alejandro Miñán; Alejandra Bosch; Peter Lasch; Maren Stämmler; Diego Omar Serra; José Degrossi; Blanca Gatti; Carlos Vay; Miguel D'aquino; Osvaldo Yantorno; Dieter Naumann

doi:10.1039/B822669E

Rapid identification of Burkholderia cepacia complex species including strains of the novel Taxon K, recovered from cystic fibrosis patients by intact cell MALDI-ToF mass spectrometry†

Alejandro Miñán,‡^a Alejandra Bosch,‡^a Peter Lasch,^b Maren Stämmler,^b Diego Omar Serra,^a José Degrossi,^c Blanca Gatti,^d Carlos Vay,^e Miguel D'aquino,^c Osvaldo Yantorno^a and Dieter Naumann*^b

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* Corresponding authors

^a CINDEFI (CONICET-La Plata), Facultad de Ciencias Exactas, UNLP, Calle 50 y 115, (1900) La Plata, Argentina

^b Robert Koch-Institut, Nordufer 20, D-13353 Berlin, Germany
E-mail: NaumannD@rki.de
Fax: +49 30 4547-2606
Tel: +49 30 4547-2259

^c Cátedra de Microbiología, Facultad de Farmacia y Bioquímica, UBA, Junin 959, Capital Federal, Junin 954 - Capital Federal - CP 1113, Argentina

^d Hospital de Niños Sor María Ludovica, Calle 14 N° 1631 CP 1900, La Plata, Argentina

^e Servicio de Bacteriología, Hospital de Clínicas, Av. Córdoba 2351 1° Piso, Ciudad de Buenos Aires, Argentina

Abstract

Two approaches based on intact cell matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (IC-MALDI-ToF MS) have been evaluated in order to discriminate and identify nine former Burkholderia cepacia complex (Bcc) species, Burkholderia contaminans belonging to the novel Taxon K, Burkholderia gladioli, and the most relevant non-fermentative (NF) Gram-negative rods recovered from cystic fibrosis (CF) sputum cultures. In total, 146 clinical isolates and 26 reference strains were analysed. IC mass spectra were obtained with high reproducibility applying a recently developed inactivation protocol which is based on the extraction of microbial proteins by trifluoroacetic acid (TFA). In a first approach, spectral analysis was carried out by means of a gel-view representation of mass spectra, which turned out to be useful to recognize specific identifying biomarkerproteins (SIBPs). A series of prominent mass peaks, mainly assigned to constitutively expressed proteins, were selected as SIBPs for identifications at the genus and species level. Two distinctive mass peaks present in B. contaminans spectra (7501 and 7900 Da) were proposed as SIBPs for the identification of this novel species. A second approach of spectral analysis based on data reduction, feature selection and subsequent hierarchical cluster analysis was used to obtain an objective discrimination of all species analysed. Both complementary modalities of analyzing complex IC-MALDI-ToF MS data open the path towards a rapid, accurate and objective means of routine clinical microbiology diagnosis of pathogens from sputum samples of CF patients.

This article is part of the themed collection: Optical Diagnosis

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Rapid identification of Burkholderia cepacia complex species including strains of the novel Taxon K, recovered from cystic fibrosis patients by intact cell MALDI-ToF mass spectrometry†

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Rapid identification of Burkholderia cepacia complex species including strains of the novel Taxon K, recovered from cystic fibrosis patients by intact cell MALDI-ToF mass spectrometry

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