In medical microbiology, the identification of microorganisms in clinical specimens is a key
step for successful therapy. In the last few years, new technologies have emerged for routine
identification, among which matrix assisted laser desorption/ionization time of flight mass spectrometry
(MALDI-TOF MS), a technology that appears very promising as it is currently becoming established in
microbiological laboratories worldwide. MALDI-TOF MS allows the identification of microorganisms
- bacteria as well as fungi - by so called intact-cell mass spectrometry, and the comparison of a
sample’s mass spectrum to reference mass spectra in a database. The key factors to the success of this
technology are: i) the fact that a uniform sample preparation procedure is utilized for many different
types of microorganisms, ii) the short time to a result, and 3) the comparatively low cost per analysis.
Additionally, mass spectrometry based identification can be readily expanded to different
microbiological fields, including food, industrial and veterinary microbiology.
In this chapter, the basic principles of MALDI-TOF MS are briefly described, followed by an
introduction to intact-cell mass spectrometry of microorganisms and mass based identification. Further,
limits of the technology are reviewed in the light of expected future developments. Finally, possible
consequences of the broad introduction of MALDI-TOF MS based on microbial identification systems
for practical and theoretical issues of medical microbiology are discussed.
Keywords: Mass Spectrometry, MALDI-TOF MS, Mass Spectra, Diagnostic Microbiology, Microbial
Taxonomy, Spectral comparison.
