Volatile Organic Compound and Metabolite Signatures as Pathogen Identifiers and Biomarkers of Infectious Disease

Abstract

Volatile organic compound (VOC)-based diagnostics have great potential to be the next generation of screening tools for pathogen identification and infectious disease management. VOCs are low molecular weight metabolic compounds that have high vapor pressures and low boiling points, both of which facilitate evaporation at ambient temperatures. There is increasing evidence that particular VOCs, or profiles of VOCs, are unique to various disease states. Different pathogenic species have been found to produce characteristic profiles of VOCs by virtue of their distinct metabolisms. The detection of these metabolite profiles from patient samples could provide an effective means of rapid, non-invasive pathogen identification, thus enabling early diagnosis and treatment. In this review, we will discuss the potential of VOC profiles to be utilized as biomarkers of pathogenic infection, with a focus on bacterial pathogens. Herein we describe the common methods for clinical VOC sample collection, provide an overview of the various instruments and techniques used for VOC detection and analysis, and summarize the key findings of recent studies that have investigated VOC biomarkers in various infectious diseases. We will also discuss the challenges associated with translating VOC analysis into a clinical diagnostic tool.

Thermophilic and non-thermophilic Campylobacter species Emits Distinct Volatile Organic Compounds in Different Culture Media and Growth Phases

“…The bacterial VOCs are detected by means of gas chromatographic techniques, particularly the gas chromatography-mass spectrometry (GC-MS), which is generally preceded by a sample preparation 19,23 .…”

“…However, owing to the lack of standardized methods, the nature of targeted sample matrix (i.e., the composition and the analytes' properties), the experimental requirements and constraints (i.e., costs and instrumental issues, etc. ), select the most suitable sampling procedure to serve the purpose of VOC ngerprinting is challenging 25,23,26 . Nevertheless, sorption tube approach seems to be a suitable strategy that is widely adopted for gas sampling as it could retain a range of compatible VOCs at ambient temperature subjected to the interaction between the analytes and the sorbent material; the retained content could be desorbed for subsequent measurement 25,26 .…”

Rapid in vitro differentiation of bacteria by ion mobility spectrometry

“…Ion mobility spectrometry (IMS) on the other hand has many advantages for diagnostics. It is fast and very sensitive with detection limits of down to parts-per-trillion (ppt) (Westhoff et al 2009;Hong-Geller and Adikari 2018). In addition, it is already used as on-site tool for the detection of chemical warfare agents, explosives, and drugs at airports (Hopfgartner 2019).…”

The Emergence of Insect Odorant Receptor-Based Biosensors

“…Detection of VOCs was demonstrated in a wide range of applications with early reports focusing on environmental exogenous VOCs [1] due to their adverse effects on human health [2][3][4]. The possibility of using bacterial VOC biomarkers as a diagnostic approach has drawn much attention lately [5] since different pathogenic species produce a characteristic VOC profile [6,7]. These "bacterial signatures" have been studied using different separation techniques coupled with mass spectrometry [8][9][10].…”