Volatile Organic Compounds Analysis by PTR-TOF-MS for Screening Respiratory Infections Using Exhaled Breath.

Overview

Emerging respiratory diseases are a global health threat. Viruses such as influenza and coronaviruses have been the main cause of pandemics over the last century. In general, the impact of these respiratory infections is not limited to pandemic risks. Indeed, some pathogens also induce seasonal epidemics with a significant medical and economic burden. It is therefore essential to strengthen global surveillance, warning systems and early diagnosis capabilities for pathogens responsible for respiratory infections. One promising and recognized approach is the analysis of exhaled air, which contains a complex mixture of volatile organic compounds (VOCs), also known as the "volatilome". The volatilome is influenced by the patient's metabolism, immune system and microbiome. It can be disturbed by the presence of a pathogen. A possible approach to study the human volatilome is called the "on-line" method. Among the technologies capable of performing online analysis, analyzers using TOF (time-of-flight) technology separate ions according to velocity differences after acceleration by a fixed potential, and then measure all mass/charge ratios simultaneously. The data obtained takes the form of a mass spectrum composed of a multitude of peaks representing the abundance of each detected chemical species contained in the exhalation. The sensitivity and measurement speed of instruments using PTR-TOF-MS (Proton Transfer Reaction - Time of Flight - Mass spectrometer) technology enable real-time monitoring of the exhalation process, making it possible to analyze exhaled air as a function of time. PTR-TOF-MS instruments are usually compact in design, enabling them to be deployed in environments such as hospital emergency wards or mass screening centers. The aim of the VORTEX-1 study is to include patients presenting with signssymptoms of respiratory infections, irrespective of microbiological etiology, to approximate a routine clinical context, thus including infections of various viral or bacterial origins. In addition, a so-called "control" group will also be sampled, made up ofcomposed by healthy subjects (with nowithout respiratory infections or serious or chronic pathologies at the time of sampling). In parallel with the study of the chemical composition of the exhaled air of these patients, and to further our understanding of the factors influencing the volatilome, a combined exploratory analysis of the respiratory microbiota, the host response at the time of infection, and the pathogen(s) responsible for the infectious episode is required. To date, no such analysis exists in the scientific literature, probably due to the technical and logistical complexity of integrating data from multiple sources and the lack of a multidisciplinary consortium with the necessary expertise.In parallel with the study of the chemical composition of the exhaled air of these patients, and in order to go further in understanding the factors influencing the volatilome, a combined exploratory analysis of the respiratory microbiota, the host response at the time of infection and the pathogen(s) responsible for the infectious episode is required. To date, no such analysis exists in the scientific literature, probably due to the technical and logistical complexity of integrating data from multiple sources, but also to the absence of a multidisciplinary consortium capable of bringing together all the necessary expertise within the same project. The detection of specific VOCs could considerably improve and facilitate the diagnosis of these respiratory diseasesinfections. This research could revolutionize the diagnosis of respiratory infections by offering a rapid, non-invasive and easily scalable alternative to conventional diagnostic methods such as PCR tests, which require nasopharyngeal sampling. In parallel with the study of the chemical composition of the exhaled air of these patients, and to further our understanding of the factors influencing the volatilome, a combined exploratory analysis of the respiratory microbiota, the host response at the time of infection, and the pathogen(s) responsible for the infectious episode is required. To date, no such analysis exists in the scientific literature, probably due to the technical and logistical complexity of integrating data from multiple sources and the lack of a multidisciplinary consortium with the necessary expertise. The detection of specific VOCs could considerably improve and facilitate the diagnosis of these respiratory infections. by offering a rapid, non-invasive and easily scalable alternative to conventional diagnostic methods such as PCR tests.