MALDI-TOF MS in Microbiology Schubert and Kostrzewa

Within less than a decade matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has become a gold standard for microbial identification in clinical microbiology laboratories. Besides identification of microorganisms the typing of single strains as well as the antibiotic and antimycotic resistance testing has come into focus in order to speed up the microbiological diagnostic. However, the full potential of MALDI-TOF MS has not been tapped yet and future technological advancements will certainly expedite this method towards novel applications and enhancement of current practice. So, the following chapter shall be rather a brainstorming and forecast of how MALDI-TOF MS will develop to influence clinical diagnostics and microbial research in the future. It shall open up the stage for further discussions and does not claim for overall validity. Introduction Within less than a decade MALDI-TOF MS has entered the microbiological diagnostic laboratories around the world providing a fast, cheap and reliable tool for identification of bacteria and fungi cultivated on agar plates or in liquid media (Kostrzewa and Schubert, 2016; Schubert and Kostrzewa, 2016). First steps have been made to introduce MALDI-TOF MS for antibiotic and antimycotic resistance testing as well as for some typing applications. The future development of MALDI-TOF MS for clinical diagnostics will likely be driven by technical advances, on the machine and software side as well as regarding sample preparation, and integration of MALDI-TOF MS in fully automated workflows pushing forward already established application. On the other hand, new fields of application for MALDI-TOF MS may be envisaged extending the use on imaging and maybe even in vivo applications. This development should bring together different laboratory disciplines like patho log is ts , medica l microb io log is t and pharmacologists. Improvement of current MALDI-TOF MS technologies One of the foreseeable main developments for microbiological laboratories in the next future will be the implementation of automated processes in the lab workflow, in particular in diagnostic laboratories. Several diagnostic companies, e.g. BD Kiestra (Drachten, The Netherlands) and Copan (Brescia, Italy) have developed fully automated workflows for the culture based microbiological laboratories (Matthews and Deutekom, 2011). Here, the allocation and barcode labelling of agar plates, streaking of the samples onto the plates and inoculation of liquid culture media as well as the transfer of culture media to specialized incubators is managed by a fully automated robotic system. Moreover, growth on the plates can be monitored and documented by digital imaging at defined time points. The complete implementation of MALDI-TOF MS in these workflows, however, is still in its infancy as several steps in the 'from-the sample-to-result' workflow are still done manually. Today, the identification using MALDI-TOF MS is performed on demand initiated by lab personnel at different time points. The selection of respective colonies for further identification is essentially based on the skills and experience of the staff. In future, a fully automated, seamless MALDI-TOF MS workflow for identification could be triggered by software assessing the images of the agar plate for putatively different colonies. These colonies then could be prepared automatically for the MALDI-TOF measurement. Subsequently, sample targets might be transferred to and introduced into the mass !17 Curr. Issues Mol. Biol. (2017) 23: 17-20. caister.com/cimb MALDI-TOF MS in the Microbiology Laboratory: