Identification of clinical isolates of anaerobic bacteria using matrix-assisted laser desorption ionization-time of flight mass spectrometry
We evaluated the use of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF) for the rapid identification of anaerobic bacteria that had been isolated from clinical specimens and previously identified by 16s rRNA sequencing. The Bruker Microflex MALDI-TOF instrument with the Biotyper Software was used. We tested 152 isolates of anaerobic bacteria from 24 different genera and 75 different species. A total of 125 isolates (82%) had Biotyper software scores greater than 2.0 and the correct identification to genus and species was made by MALDI-TOF for 120 (79%) of isolates. Of the 12 isolates with a score between 1.8 and 2.0, 2 (17%) organisms were incorrectly identified by MALDI-TOF. Only 15 (10%) isolates had a score less than 1.8 and MALDI-TOF gave the wrong genus and species for four isolates, the correct genus for two isolates, and the correct genus and species for nine isolates. Therefore, we found the Bruker MALDI-TOF MicroFlex LT with an expanded database and the use of bacteria extracts rather than whole organisms correctly identified 130 of 152 (86%) isolates to genus and species when the cut-off for an acceptable identification was a spectrum score ≥1.8.
- 1.Cherkaoui A, Hibbs J, Emonet S, Tangomo M, Girard M, Francois P, Schrenzel J (2010) Comparison of two matrix-assisted laser desorption ionization-time of flight mass spectrometry methods with conventional phenotypic identification for routine identification of bacteria to the species level. J Clin Microbiol 48(4):1169–1175PubMedCrossRefGoogle Scholar
- 3.Ferroni A, Suarez S, Beretti J-L, Dauphin B, Bille E, Meyer J, Bougnoux M-E, Alanio A, Berche P, Nassif X (2010) Real-time identification of bacteria and Candida species in positive blood culture broths by matrix-assisted laser desorption ionization-time of flight mass spectrometry. J Clin Microbiol 48(5):1542–1548PubMedCrossRefGoogle Scholar
- 5.Mellmann A, Cloud J, Maier T, Keckevoet U, Ramminger I, Iwen P, Dunn J, Hall G, Wilson D, LaSala P, Kostrzewa M, Harmsen D (2008) Evaluation of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry in comparison to 16s rRNA gene sequencing for species identification of nonfermenting bacteria. J Clin Microbiol 46(6):1946–1954PubMedCrossRefGoogle Scholar
- 7.Justesen US, Holm A, Knudsen E, Anderson LB, Jensen TG, Kemp M, Skov MN, Gahrn-Hansen B, MØller JK (2011) Species identification of clinical isolates of anaerobic bacteria: a comparison of two matrix-assisted laser desorption ionization-time of flight mass spectrometry systems. J Clin Microbiol. 12 October 2011 [EPub ahead of print]Google Scholar
- 11.Christner M, Rohde H, Wolters M, Sobottka I, Wegscheider K, Aepfelbacher M (2010) Rapid identification of bacteria from positive blood culture bottles by use of matrix-assisted laser desorption-ionization time of flight mass spectrometry fingerprinting. J Clin Microbiol 48(5):1584–1591PubMedCrossRefGoogle Scholar
- 14.Alatoom AA, Cunningham SA, Ihde SM, Mandrekar J, Patel R (2011) Comparison of direct colony method versus extraction method for identification of gram-positive cocci by use of Bruker Biotyper matrix-assisted laser desorption ionization-time of flight mass spectrometry. J Clin Microbiol 49(8):2868–2873PubMedCrossRefGoogle Scholar