Christopher Cox (Presenter)
Colorado School of Mines
Bio: I received my B.S. in Microbiology and Biochemistry from the University of Oklahoma. I then studied under Dr. Michael Gilmore, first at the OU Med. School to obtain a Master’s in Microbiology, then at Harvard where I did my dissertation research and completed my Ph.D. I came to CSM as a postdoc to investigate the use of phages and various forms of mass spectrometry for molecular biomarker measurement and microorganism ID. Now, as a junior member of the research faculty as CSM, my research focuses on development of new bacterial and fungal diagnostics. By focusing on phage amplification or bacterial and fungal fatty acid measurement by LFI, MALDI or MOLI-MS, Raman spectrometry and lateral flow capillary concentration (LFCC) (a novel technology that I invented), we have developed more accurate, user-friendly diagnostic approaches with broad commercialization potential.
Authorship: Christopher R. Cox (1), Kirk R. Jensen (2), NIcholas R. Saichek (1) and Kent J. Voorhees (1)
(1) Colorado School of Mines, Department of Chemistry, Golden, CO; (2) Osaka University, Osaka, Japan.
| Short Abstract Diagnostic MALDI is an important tool for clinical pathogen ID. While relatively effective for bacteria, MALDI protein profiling has had little impact on fungal diagnosis because it often cannot differentiate closely related isolates expressing similar or identical proteins. This results in mis-ID or failure to ID, necessitates additional lengthy biochemical tests, and delays treatment. New approaches are needed to improve accuracy and reduce turnaround. We investigated Metal Oxide Laser Ionization (MOLI) MS fatty acid analysis for ID of clinical yeasts and molds that are historically difficult or impossible to ID with commercial MALDI instruments. The energy inherent to the MALDI laser allowed for in situ metal oxide-catalyzed lipid fragmentation into taxonomically useful fatty acids. This resulted in near 100% accurate ID of Candida, Cryptococcus, Rhodotorula and Saccharomyces. |
Long Abstract
Diagnostic biomarker fingerprinting by matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) has become an important and increasingly utilized tool for diagnostic microorganism identification in clinical, industrial and food safety laboratories worldwide. While relatively effective for bacterial identification, protein profiling-based mass spectrometric techniques have had little impact on clinical mycology or pathogenic fungal diagnostics.
Species level identification of yeasts and multicellular molds is one of the most challenging tasks in diagnostic microbiology. Currently available commercial systems, while relatively rapid and reasonably user friendly, have some fundamental drawbacks that greatly limit their accuracy and overall utility for species or stain level fungal identification. Most notably, protein profile-based MALDI approaches have been disappointing because they cannot differentiate closely related fungi that in many cases express similar if not identical proteins resulting in misidentification or, quite often, a complete failure to provide any reliable identification at all. This leads to the need for additional, lengthy biochemical testing, which adds significant time and expense and further delays treatment.
To address this challenge, we employed Metal Oxide Laser Ionization (MOLI) MS to facilitate in situ fragmentation of fungal lipids directly on the MALDI target plate. This resulted in ionization of taxonomically viable fatty acids using the energy inherent to the MALDI laser. MOLI MS-generated fatty acid profiles were collected from a diverse collection of clinical Candida, Cryptococcus, Rhodotorula and Saccharomyces isolates resulting in 100% correct, reproducible classification at the species and strain level as determined by principal component analysis and statistically validated by leave–one-out cross validation (CV).
References & Acknowledgements:
| Description | Y/N | Source |
| Grants | no | |
| Salary | no | |
| Board Member | no | |
| Stock | no | |
| Expenses | no |
IP Royalty: no
| Planning to mention or discuss specific products or technology of the company(ies) listed above: | no |