The recent and
widespread adoption of MALDI-TOF mass spectrometry (MS) for identification of
microorganisms is an example of the power of integrating analytical chemistry
and microbiology. MALDI-TOF MS has revolutionised clinical microbiology by
providing a universal, rapid, low cost and robust method of routine
identification of many clinically important bacteria and yeasts. Conventional MALDI-TOF
MS protocols typically involve sampling of colonies directly from solid culture
media. However, recent developments include the direct identification of
microorganisms from urine specimens and blood culture bottles. These obviate
the need for culturing on solid media, thus saving costs and improving
turn-around times. We have recently developed a similar scheme for detection of
food-borne pathogens directly from enrichment broths. Further applications
beyond routine identification can improve the versatility of MALDI-TOF MS
systems and provide additional information relevant to clinical care and
epidemiological investigations. A particularly attractive aspect of MALDI-TOF
MS is that the acquired data (i.e. spectral profiles produced by different
bacteria) can be interrogated at different levels to yield information beyond
the genus and species levels to sub-species and even strain type. Recently,
MALDI-TOF MS has been investigated for its ability to determine antimicrobial
drug resistance with some very encouraging results. Other diagnostic microbiology
applications of MS take advantage of recent developments in high-resolution analytical
platforms (e.g. liquid and gas chromatography). Such developments have
facilitated the rapid, accurate and quantitative analysis of the metabolome of
microorganisms, allowing microbial activity to be determined in clinical (e.g.
blood), environmental (e.g. water) and food samples.