Reproducible breath metabolite changes in children with SARS-CoV-2 infection

Breath collection protocol for SARs-CoV-2 testing in an ambulatory setting

Breath research during the SARS-CoV-2 pandemic offers an opportunity for discovery of a rapid point-of-care screening test, but also introduces a hazard to researchers collecting, transporting and analyzing breath samples not only for COVID -19 research, but all human breath-related research during the ongoing pandemic. Safe workflows to protect study participants and staff collecting and analysing the samples must be determined. We developed a SARS-CoV-2 breath test protocol for collection and processing of breath samples in ambulatory care COVID-19 testing sites and prospectively evaluated the protocol. 528 breath samples from 393 participants at COVID-19 testing sites were safely collected, transported, stored, and analysed with zero transmission to staff. Our method development for the safe collection of samples included the examination of 2 different filters for added safety. We discovered the use of filters leads to increased sample contamination and/or reduction of endogenous features in breath samples. Personal protective equipment (PPE) is essential for all breath collection while SARS-CoV-2 remains wide-spread through the general population. We have demonstrated that use of completely disposable breath collection devices and PPE, are sufficient for safe collection. Filters in the workflow add complexity to an already complex breath matrix and may compromise bio-safety.

Pathophysiology of SARS-CoV-2 Infection in the Upper Respiratory Tract and Its Relation to Breath Volatile Organic Compounds

Among the many products of metabolic processes are volatile organic compounds (VOCs). In the airways, these volatile metabolites are emitted through breathing and thus are easily sampled for analysis. Recent work has connected the functions and structure of the human microbiome with health and disease. Alteration in microbial function in this context can result in differences in metabolite composition, including that of VOCs, presenting the possibility of a new noninvasive method for clinical diagnosis. Screening methods that assess VOCs arising from changes in the airway microbiome could be highly useful in diagnosing viral upper respiratory tract infections (URTIs), e.g., COVID-19, which are highly contagious and have an enormous public health impact worldwide. A rapid noninvasive screening test for URTIs would pose major advantages in containing the disease. As early evidence shows that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection alters the human microbiome (both in the gut and the respiratory tract), we propose that detection of a VOC signature of an altered nasal microbiome could be fruitful as a rapid noninvasive measure of URTI in general and of SARS-CoV-2 in particular.

Detecting SARS-CoV-2 in the Breath of COVID-19 Patients

In the COVID-19 outbreak year 2020, a consensus was reached on the fact that SARS-CoV-2 spreads through aerosols. However, finding an efficient method to detect viruses in aerosols to monitor the risk of similar infections and enact effective control remains a great challenge. Our study aimed to build a swirling aerosol collection (SAC) device to collect viral particles in exhaled breath and subsequently detect SARS-CoV-2 using reverse transcription polymerase chain reaction (RT-PCR). Laboratory tests of the SAC device using aerosolized SARS-CoV-2 pseudovirus indicated that the SAC device can produce a positive result in only 10 s, with a collection distance to the source of 10 cm in a biosafety chamber, when the release rate of the pseudovirus source was 1,000,000 copies/h. Subsequent clinical trials of the device showed three positives and 14 negatives out of 27 patients in agreement with pharyngeal swabs, and 10 patients obtained opposite results, while no positive results were found in a healthy control group (n = 12). Based on standard curve calibration, several thousand viruses per minute were observed in the tested exhalations. Furthermore, referring to the average tidal volume data of adults, it was estimated that an exhaled SARS-CoV-2 concentration of approximately one copy/mL is detectable for COVID-19 patients. This study validates the original concept of breath detection of SARS-CoV-2 using SAC combined with RT-PCR.