Differentiation of Cystic Fibrosis-Related Pathogens by Volatile Organic Compound Analysis with Secondary Electrospray Ionization Mass Spectrometry

Abstract

Identifying and differentiating bacteria based on their emitted volatile organic compounds (VOCs) opens vast opportunities for rapid diagnostics. Secondary electrospray ionization high-resolution mass spectrometry (SESI-HRMS) is an ideal technique for VOC-biomarker discovery because of its speed, sensitivity towards polar molecules and compound characterization possibilities. Here, an in vitro SESI-HRMS workflow to find biomarkers for cystic fibrosis (CF)-related pathogens P. aeruginosa, S. pneumoniae, S. aureus, H. influenzae, E. coli and S. maltophilia is described. From 180 headspace samples, the six pathogens are distinguishable in the first three principal components and predictive analysis with a support vector machine algorithm using leave-one-out cross-validation exhibited perfect accuracy scores for the differentiation between the groups. Additionally, 94 distinctive features were found by recursive feature elimination and further characterized by SESI-MS/MS, which yielded 33 putatively identified biomarkers. In conclusion, the six pathogens can be distinguished in vitro based on their VOC profiles as well as the herein reported putative biomarkers. In the future, these putative biomarkers might be helpful for pathogen detection in vivo based on breath samples from patients with CF.

Non-invasive monitoring of microbiota and host metabolism using Secondary electrospray ionization-Mass spectrometry

“…The Headspace-SESI system consists of an in-house developed custom-made headspace sampling system (Fig 1C and Fig S1, adapted from [61]), a commercial SESI source (SuperSESI, Fossiliontech, Spain) and an Orbitrap mass spectrometer (Q-Exactive Plus, Thermo Scientific, San Jose, CA). All three EAM strains were able to grow in the Headspace-SESI system under the measurement condition (Fig S4A), including the strictly anaerobic bacteria E. rectale .…”

Applications of ambient ionization mass spectrometry in 2021: An annual review

“…Kaeslin et al. used SESI‐HRMS for the direct headspace sampling of six CF‐related pathogen cultures, specifically P. aeruginosa , S. pneumoniae , S. aureus , H. influenzae , E. coli and S. maltophilia 141 . Analyzing a total of 180 samples, a machine learning algorithm was developed and is capable of differentiating between the pathogens based on distinct chemical signatures.…”

“…One particular protein, the 50S ribosomal protein L29, was detected in 75% of the ESKAPE species studied, thus, could be used as a potential biomarker for some ESKAPE pathogens.AIMS has also been used to study pathogens related to cystic fibrosis, a condition in which patients are particularly prone to lung infections. Kaeslin et al used SESI-HRMS for the direct headspace sampling of six CF-related pathogen cultures, specifically P. aeruginosa, S. pneumoniae, S. aureus, H. influenzae, E. coli and S. maltophilia 141. Analyzing a total of 180 samples, a machine learning algorithm was developed and is capable of differentiating between the pathogens based on distinct chemical signatures.…”

Rapid detection of Staphylococcus aureus and Streptococcus pneumoniae by real-time analysis of volatile metabolites

“…However, this method requires time-consuming sample preparation, limiting the possibilities of providing quicker results than MALDI-TOF-based analyses. Alternative real-time mass spectrometric techniques such as SIFT-MS and secondary electrospray ionization–high resolution mass spectrometry (SESI-HRMS) ( Ballabio et al., 2014 ; Bean et al., 2014 ; Kaeslin et al., 2021 ; Lee and Zhu, 2020 ; Li et al., 2019 ; Li and Zhu, 2018 ; Zhu et al., 2010 , 2013a , 2013b , 2013c ; Zhu and Hill, 2013 ) can provide analyses of VOCs on the fly, thus potentially shortening time-to-results.…”