Identification of micro-organisms, using MALDI-TOF-MS, uses a synthetic reference spectrum for comparison with the mass spectrum to register the micro-organism under study

Identifying micro-organisms uses matrix assisted laser desorption ionization/time of flight/mass spectrometry (MALDI-TOF-MS), is new. A database (DB) of reference spectra has mass spectra of some known micro-organisms. The reference spectrum (REF) uses synthetic reference spectra (REFS), which gather a reduced number of specific signals for a given micro-organism compared with natural mass spectra. Identifying micro-organisms by MALDI-TOF-MS, the signals from a synthetic reference spectrum contain at least one identification signal (Sid) relating to a single molecular cell component of each micro-organism. The molecular cell component is a peptide, protein, a ribonucleic acid (RNA) and/or a lipid, a ribosomal protein and especially a protein of a large ribosome sub-unit. The signals from a synthetic reference spectrum contain at least one empirical signal (Sem), specific for a given micro-organism, through comparison of the mass spectra of known micro-organisms. The comparison is visual and/or computer assisted. The criteria for the generation of an empirical signal are a given minimum frequency for the presence of a signal in a number of mass spectra for the same micro-organism, and a given minimum signal intensity. A signal is represented by a pair of coordinates composed of a mass or a mass/charge ratio as the X-coordinate, and an absolute or relative intensity as the Y-coordinate. The synthetic reference spectrum gives 5-30 signals and preferably 10-15. The mass spectra are registered from cells which have not been prepared. The analysis of the similarity of the mass spectra of the micro-organisms to be identified with the reference spectra stored in the database is restricted to a comparison of the signals contained in the reference spectra. The analysis of the similarity of the signals in the reference spectra uses weighting. Die Erfindung betrifft ein Verfahren zur Identifizierung von Mikroorganismen mittels Matrix-assisted-Laser-Desorption-Ionisation Time-of-Flight Massenspektrometrie (MALDI-TOF-MS), wobei eine Datenbank mit Referenzspektren, bestehend aus Massenspektren einer Anzahl bekannter Mikroorganismen, erstellt wird, ein MALDI-TOF-Massenspektrum (Probenspektrum) einer Probe eines zu identifizierenden Mikroorganismus aufgenommen wird und eine Ähnlichkeitsanalyse des Massenspektrums des zu identifizierenden Mikroorganismus mit den in der Datenbank enthaltenen Referenzspektren durchgeführt wird. DOLLAR A Es ist vorgesehen, dass als Referenzspe