The principle behind identification of microorganisms with MALDI Biotyper is the comparison of the mass spectrum of an unknown organism with a library of reference mass spectra - the MSPs (main spectra) of the MALDI Biotyper. It’s obvious that the specificity of species identification depends on the species/strain coverage of the reference spectrum library. Bruker therefore invested substantial resources to collecting as many strains as possible to build up the most comprehensive library. The major contributors are the 26 laboratories of the International Mycobacterium Consortium, providing well characterized clinical strains from which more than 470 reference entries have been derived.
In the course of reference spectra creation for the MBT Mycobacteria IVD library, mycobacteria were cultivated on liquid and solid media and resulting spectra compared. To prevent redundant reference entries (MSPs), in general, spectra from only one culture medium (liquid or solid) are included in the library when no differences were observed. For mycobacteria species where only one or two strains were available, references from both types of media are included. Hence the library can conveniently be applied for samples independent from growth on liquid or solid medium.