Evaluation of Matrix-Assisted laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) in Comparison to 16S rRNA Gene Sequencing for Species Identification of Nonfermenting Bacteria
| Type: | Application |
Scientific Paper |
Clinical Proteomics |
| Number: | Technology |
10.1128/JCM.00157-08 |
MALDI-TOF |
| Year | Products |
2008 |
MALDI Biotyper |
| Author | |
A. Mellmann, J. Cloud, T. Maier, U. Keckevoet, I. Ramminger, P. Iwen, J. Dunn, G. Hall, D. Wilson, P. LaSala, M. Kostrzewa, D. Harmsen |
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| Reference | |
J. Clin. Microbiol. 46:1946-1954. |
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Abstract |
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Nonfermenting bacteria are ubiquitous environmental opportunists causing infection especially in compromised patients. Due to their limited biochemical reactivity and different morphotypes, misidentification by classical phenotypic means occurs frequently. Therefore, we evaluated matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for species identification. Using 248 nonfermenting culture collection strains composed of 37 genera most relevant for human infections, a reference databa<x>se was established for MALDI-TOF MS-ba<x>sed species identification following manufacturer's recommendations for microflex measurement and MALDI BioTyperTM software (Bruker Daltonik GmbH, Leipzig, Germany), i.e. using a mass range of 2,000 to 20,000 Dalton and a new pattern matching algorithm. To evaluate the databa<x>se, 80 blind-coded clinical nonfermenting bacterial strains were analyzed. As a reference method for species designation, partial 16S rRNA gene sequencing was applied. Using 16S rRNA gene sequencing, 57 of the 80 isolates produced unique species identification (≥ 99% sequence similarity); 11 further isolates gave ambiguous results at this threshold and were rated as identified at genus level only. 10 isolates were identified to genus level (≥ 97% similarity) and 2 isolates were below this threshold and counted as not identified and excluded from further analysis. MALDI-TOF MS identified 67 of the included 78 isolates (85.9%) in agreement with the reference method, 9 were misidentified and 2 unidentified. Identification of 10 randomly selected strains was 100% correct using 3 different mass spectrometers and 4 different cultivation media. Thus, MALDI-TOF MS-ba<x>sed species identification of nonfermenting bacteria provided accurate and reproducible results within 10 minutes without any substantial costs for consumables.
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