Identification of Mycobacterium Species by MALDI-TOF Mass Spectrometry

Matrix-assisted laser desorption ionization - time-of-flight (MALDI-TOF) mass spectrometry enables to identify microorganisms by comparison of the protein content with reference spectra in the database. The aim of this study was to evaluate the efficacy of phenotypic identification of mycobacteria by MALDI-TOF mass spectrometry in laboratory practice. Seventy five isolates of mycobacteria were identified by molecular and phenotypic method, and the results were compared by MALDI-TOF. For MALDI-TOF, material was processed according to the Bruker Daltonics protocol and Mycobacterial Library database version 2.0, with 313 reference mycobacteria spectra. All except one of the 72 isolates agreed with regard to the species and genus by both methods. Forty three isolates were identified as the M. tuberculosis complex by MALDI-TOF. Thirty one isolates of nontuberculous mycobacteria were consistently identified by both methods to the species level. We conclude that MALDI-TOF mass spectrometry is an accurate method of bacterial identification. Simplicity, speed, and economic availability of the method makes it suitable for mycobacteria identification in a routine laboratory.