This Article Full Text Full Text (PDF) Other Versions of this Article: JCM.00569-08v1 46/10/3361    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Google Scholar Articles by Degand, N. Articles by Ferroni, A. PubMed PubMed Citation Articles by Degand, N. Articles by Ferroni, A.

 Previous Article  |  Next Article 

Journal of Clinical Microbiology, October 2008, p. 3361-3367, Vol. 46, No. 10
0095-1137/08/$08.00+0     doi:10.1128/JCM.00569-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Identification of Nonfermenting Gram-Negative Bacilli Isolated from Cystic Fibrosis Patients

Assistance Publique-Hôpitaux de Paris, Laboratoire de Microbiologie, Hôpital Necker-Enfants Malades, Paris, France,¹ Université Paris Descartes, Faculté de médecine, Paris, France,² Service de Pneumologie Pédiatrique,³ Service de Pédiatrie Générale, Hôpital Necker-Enfants Malades, Paris, France,⁴ Observatoire Cepacia, Hôpital Purpan, Toulouse, France⁵

Received 25 March 2008/ Returned for modification 12 May 2008/ Accepted 22 July 2008

The identification of nonfermenting gram-negative bacilli isolated from cystic fibrosis (CF) patients is usually achieved by using phenotype-based techniques and eventually molecular tools. These techniques remain time-consuming, expensive, and technically demanding. We used a method based on matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) for the identification of these bacteria. A set of reference strains belonging to 58 species of clinically relevant nonfermenting gram-negative bacilli was used. To identify peaks discriminating between these various species, the profile of 10 isolated colonies obtained from 10 different passages was analyzed for each referenced strain. Conserved peaks with a relative intensity greater than 0.1 were retained. The spectra of 559 clinical isolates were then compared to that of each of the 58 reference strains as follows: 400 Pseudomonas aeruginosa, 54 Achromobacter xylosoxidans, 32 Stenotrophomonas maltophilia, 52 Burkholderia cepacia complex (BCC), 1 Burkholderia gladioli, 14 Ralstonia mannitolilytica, 2 Ralstonia pickettii, 1 Bordetella hinzii, 1 Inquilinus limosus, 1 Cupriavidus respiraculi, and 1 Burkholderia thailandensis. Using this database, 549 strains were correctly identified. Nine BCC strains and one R. mannnitolilytica strain were identified as belonging to the appropriate genus but not the correct species. We subsequently engineered BCC- and Ralstonia-specific databases using additional reference strains. Using these databases, correct identification for these species increased from 83 to 98% and from 94 to 100% of cases, respectively. Altogether, these data demonstrate that, in CF patients, MALDI-TOF-MS is a powerful tool for rapid identification of nonfermenting gram-negative bacilli.

Published ahead of print on 6 August 2008.