Multi-centre evaluation of mass spectrometric identification of anaerobic bacteria using the VITEK® MS system

• Published in: Clinical microbiology and infection Vol. 20; no. 4; pp. 335 - 339
• Main Authors: Garner, O., Mochon, A., Branda, J., Burnham, C.-A., Bythrow, M., Ferraro, M., Ginocchio, C., Jennemann, R., Manji, R., Procop, G.W., Richter, S., Rychert, J., Sercia, L., Westblade, L., Lewinski, M.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-04-2014; Elsevier Limited
• Subjects: Anaerobe; Bacteria; Bacteria, Anaerobic - chemistry; Bacteria, Anaerobic - classification; Bacteria, Anaerobic - isolation & purification; bacterial identification; Bacterial Infections - diagnosis; Bacteriological Techniques - methods; clinical microbiology; Desorption; Humans; Ions; Mass spectrometry; matrix-assisted laser desorption ionization time-of-flight mass spectrometry; Sensitivity and Specificity; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization - methods; VITEK-MS; clinical microbiology; Anaerobe; bacterial identification; matrix-assisted laser desorption ionization time-of-flight mass spectrometry; VITEK-MS
• ISSN: 1198-743X; 1469-0691
• DOI: 10.1111/1469-0691.12317

Accurate and timely identification of anaerobic bacteria is critical to successful treatment. Classic phenotypic methods for identification require long turnaround times and can exhibit poor species level identification. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is an identification method that can provide rapid identification of anaerobes. We present a multi-centre study assessing the clinical performance of the VITEK® MS in the identification of anaerobic bacteria. Five different test sites analysed a collection of 651 unique anaerobic isolates comprising 11 different genera. Multiple species were included for several of the genera. Briefly, anaerobic isolates were applied directly to a well of a target plate. Matrix solution (α-cyano-4-hydroxycinnamic acid) was added and allowed to dry. Mass spectra results were generated with the VITEK® MS, and the comparative spectral analysis and organism identification were determined using the VITEK® MS database 2.0. Results were confirmed by 16S rRNA gene sequencing. Of the 651 isolates analysed, 91.2% (594/651) exhibited the correct species identification. An additional eight isolates were correctly identified to genus level, raising the rate of identification to 92.5%. Genus-level identification consisted of Actinomyces, Bacteroides and Prevotella species. Fusobacterium nucleatum, Actinomyces neuii and Bacteroides uniformis were notable for an increased percentage of no-identification results compared with the other anaerobes tested. VITEK® MS identification of clinically relevant anaerobes is highly accurate and represents a dramatic improvement over other phenotypic methods in accuracy and turnaround time.