MALDI-TOF mass spectrometry

Mass spectrometry (MS), a general method for molecular detection and identification, has been in use for at least 50 years. New applications, such as MALDI-TOF-MS are currently under development, raising new prospects in different sectors of the Biosciences. The basic stages of the MALDI-TOF-MS method are the following: Ionization of macro-molecules, mainly proteins, which derive from a microbiological sample which is prepared easily and rapidly; acceleration of these ions towards the detector area through a vacuum space, under controlled conditions; spectrum presentation of the detected signals; molecular identification according to the mass/charge ratio. Maintenance of appropriate conditions during the preparation and placement of the sample on the special target plate, and the choice of the solvent and the matrix that will be used are fundamental for accurate microbiological identification. As regards the basic discrimination between Gram-positive and Gram-negative bacteria, two different approaches are currently in use, characterized by different strategies on the choice of the matrix. The final stage is comparison of the findings with a continuously increasing spectra database. The application of the MALDI-TOF-MS method yields characteristic mass spectral fingerprints for the samples examined, offering dynamic prospects in the field of microbiological diagnosis.