MSACL 2019 EU Abstract

Development of Laser Assisted Rapid Evaporative Ionization Mass Spectrometry (LA-REIMS) as a Platform for Clinical Microbiology: The Past and the Future

Simon Cameron (1,2), Alvaro Perdones-Montero (1), Adam Burke (1), Kate Alexander-Hardiman (1), Monica Rebec (3); Zoltan Takats (1).
(1) Imperial College London, London, UK. (2) Queens’ University Belfast, Belfast, UK. (3) Imperial College Healthcare NHS Trust, London, UK.

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Simon Cameron (Presenter) Queen's University Belfast

Presenter Bio: I currently hold an appointment (full-time) at Queen’s University Belfast as a Vice-Chancellor’s Fellow (lecturer-equivalent position) where my group applies mass spectrometry techniques to the analysis of nutrition and microbiome development. I received my BSc (2011) and PhD (2015) from Aberystwyth University, Wales, UK in the area of molecular microbiology and metabolomics. My research interests are in the broad fields of microbiology and metabolomics. I currently coordinate (part-time) the work of the MicrobeID team within Professor Zoltan Takats’s research group at Imperial College London, which is developing rapid evaporative ionisation mass spectrometry (REIMS) as a high-throughput platform to assign taxonomic and functional classifications to microbial isolates and to the direct-from-sample profiling of mixed microbial communities.

Relevant Financial Disclosures (within past 24 months) Grant/Research Support Waters Discussing Products? YES, presenter will present educational content related to products/services of one or more ineligible company(ies) listed above. Conflict mitigation IN PROCESS.

INTRODUCTION: The introduction of MALDI-ToF has reduced the time to identification of microbial isolates. However, it still requires a user to add a matrix to assist in ionisation. Furthermore, in some instances, such as for yeasts, additional extraction steps are required for accurate species level identification. REIMS has previously been demonstrated to provide accurate species-level classification of bacteria and yeasts direct from colonies; without the need for additional preparative steps. In comparison to MALDI-ToF based platforms, REIMS utilises the lipidomic profile of bacteria and fungi to determine their species-level classification without sample preparation which expands substantially the potential application of mass spectrometry to clinical microbiology laboratories.

METHODS: An OmniGuide FELS-25A CO2 laser was incorporated into the TECAN EVO Freedom liquid handling platform previously used for electrical diathermy REIMS. The optimal set-up was previously determined and involves the use of laser power at 2W, using a repeated pulse with intervals of 40 ms and operated in the pulsatile SuperPulse mode. The resulting analyte-containing vapour produced from colony heating is aspirated into a Xevo G2-XS Q-ToF instrument (Waters Corporation, Wilmslow, UK) via a REIMS interface where it is mixed with 2-propanol infused with an external lock mass compound and collides with a heated collision surface prior to entry into the ion guide of the instrument.

RESULTS: This presentation will encompass the on-going work to develop rapid evaporative ionisation mass spectrometry (REIMS) for clinical microbiology. Three main areas will be covered: (1) development of taxonomic identification reference models for bacteria, yeast, and filamentous fungi; (2) quality control and assurance metrics for microbial speciation; (3) determination of antimicrobial susceptibilities; and (4) pathogen detection directly from clinical samples. The results show that REIMS can be used for the direct-from-culture speciation of bacteria, yeast, and filamentous fungi with high accuracy and using an identical workflow to allow easy incorporation into existing workflows. We have also established REIMS-specific metrics with regards to instrument operation, sample acquisition, and data analysis which will be discussed. Further work on extending the application of REIMS to AST and direct-from-specimen pathogen identification will also be shown.

CONCLUSIONS: LA-REIMS offers a novel mass spectrometry platform for clinical microbiology. It is capable of accurate and robust species level identifications for bacteria, yeast, and filamentous fungi directly from culture; employing the same automated, high-throughput workflow for all culture types. In addition, LA-REIMS offers the potential to expand the application of mass spectrometry beyond routine identification, into areas including antimicrobial susceptibility testing and direct-from-sample pathogen detection.