Characterization and Identification of Clinically Relevant Microorganisms Using Rapid Evaporative Ionization Mass Spectrometry

Abstract

Rapid evaporative ionization mass spectrometry (REIMS) was investigated for its suitability as a general identification system for bacteria and fungi. Strains of 28 clinically relevant bacterial species were analyzed in negative ion mode, and corresponding data was subjected to unsupervised and supervised multivariate statistical analyses. The created supervised model yielded correct cross-validation results of 95.9%, 97.8%, and 100% on species, genus, and Gram-stain level, respectively. These results were not affected by the resolution of the mass spectral data. Blind identification tests were performed for strains cultured on different culture media and analyzed using different instrumental platforms which led to 97.8-100% correct identification. Seven different Escherichia coli strains were subjected to different culture conditions and were distinguishable with 88% accuracy. In addition, the technique proved suitable to distinguish five pathogenic Candida species with 98.8% accuracy without any further modification to the experimental workflow. These results prove that REIMS is sufficiently specific to serve as a culture condition-independent tool for the identification and characterization of microorganisms.

Shotgun Lipidomic Profiling of the NCI60 Cell Line Panel Using Rapid Evaporative Ionization Mass Spectrometry

“…Detailed sampling schedules can be found in Table S Earlier studies demonstrated that REIMS is suitable to generate phospholipid profiles of various biological materials such as animal tissues, 2,27,28 human ex-vivo tissue samples of healthy and cancerous origin, 1,29 as well as microorganisms. 3,30 As analysis is performed in negative ion mode, the spectral content is similar to that described in those earlier studies featuring predominantly glycerophospholipidtype membrane lipids such as phosphatidylethanolamines -ions. A list of spectral features above a relative abundance of 2.5% with molecular assignments can be found in Table S-5.…”

“…1,3 To test the general hypothesis that REIMS spectral patterns are reproducible and sufficiently specific to differentiate between different human cancer cell lines, three different cell lines (HeLa -cervical adenocarcinoma, MES-SA -uterine sarcoma, and SNB-19 -glioblastoma) were analyzed in an experiment designed to test spectral reproducibility. The experimental scheme depicted in Figure S…”

XMS: Cross-Platform Normalization Method for Multimodal Mass Spectrometric Tissue Profiling

“…Also, mass spectrometers should provide a sufficiently good mass accuracy and resolution to obtain a low number of false positive peak annotations. If the ionization methods are the same but different mass spectrometers are used, peak annotation step and application of scaling factors might not be necessary [39].…”

Prospective applications of ultrahigh resolution proteomics in clinical mass spectrometry

“…This MALDI-TOF-MS approach is applied worldwide as a routine identification tool for typing and identifying microbial species in clinical microbiology laboratories and is known as Biotyper ™ [30]. For this purpose, alternative ambient ionization methods are also applied, such as rapid evaporative ionization MS (REIMS) [31]. In both approaches, the accurate identification of unknown microorganisms is achieved by comparing protein profiles obtained from cultured colonies to spectra in a library without any a priori knowledge [32][33][34].…”