RT-PCR diagnosis of COVID-19 from exhaled breath condensate: a clinical study

Abstract

Current diagnostic testing for coronavirus disease 2019 (COVID-19) is based on detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in nasopharyngeal swab samples by reverse transcription polymerase chain reaction (RT-PCR). However, this test is associated with increased risks of viral dissemination and environmental contamination and shows relatively low sensitivity, attributable to technical deficiencies in the sampling method. Given that COVID-19 is transmitted via exhaled aerosols and droplets, and that exhaled breath condensate (EBC) is an established modality for sampling exhaled aerosols, detection of SARS-CoV-2 in EBC offers a promising diagnostic approach. However, current knowledge on the detection and load of the virus in EBC collected from COVID-19 patients remains limited and inconsistent. The objective of the study was to quantify the viral load in EBC collected from COVID-19 patients and to validate the feasibility of SARS-CoV-2 detection from EBC as a diagnostic test for the infection. EBC samples were collected from 48 COVID-19 patients using a collection device, and viral loads were quantified by RT-PCR targeting the E gene. Changes in detection rates and viral loads relative to patient characteristics and days since disease onset were statistically evaluated. Need for mechanical ventilation was significantly associated with higher viral load (p < 0.05). Need for oxygen administration or mechanical ventilation, less than 3 d since onset, and presence of cough or fever were significantly associated with higher detection rates (p < 0.05). Among spontaneously breathing patients, viral load in EBC attenuated exponentially over time. The detection rate was 86% at 2 d since onset and deteriorated thereafter. In mechanically ventilated patients, detection rate and viral load were high regardless of days since onset. These results support the feasibility of using RT-PCR to detect SARS-CoV-2 from EBC for COVID-19 patients within 2 d of symptom onset.

Aluminium Gauze Reduces SARS-CoV-2 Viral Load in Non-Woven Masks Worn by Patients with COVID-19

“…It is not known whether aerosols that permeate through non-woven masks with 99% VFE can contain SARS-CoV-2 RNA. Several studies have demonstrated that expired breath contains SARS-CoV-2 RNA or antigen [11][12][13][14][15][16]. Ours is the first study to detect SARS-CoV-2 RNA in expired breath filtered with a non-woven mask with 99% VFE.…”

Breath analysis by ultra-sensitive broadband laser spectroscopy detects SARS-CoV-2 infection

“…Thus, in contrast to the MS approach, the variability in the CE-DFCS data measured for different research subjects is entirely preserved by the DS approach. This suggests the superior prediction performance achieved by the DS approach in the COVID-19 diagnosis can be attributed to the presence of unresolved molecules and potentially even the coron-avirus itself 21 . This discussion also highlights a key reason for the powerful capability of CE-DFCS for breath analysis: its high detection sensitivity to both resolved and unresolved molecules.…”

“…Another future endeavor is to correlate breath analysis data with viral loads quantified by RT-PCR to give more direct interpretation of the COVID-19 infection status and establish the sensitivity limit of CE-DFCS 21 .…”

Potential Use of Exhaled Breath Condensate for Diagnosis of SARS-CoV-2 Infections: A Systematic Review and Meta-Analysis

“…More recently, the SARS-CoV-2 pandemic has substantially renewed the interest towards the potential referral to EBC as diagnostic matrix for viral pathogens, and particularly for SARS-CoV-2 [ 4 , 13 , 14 , 15 , 16 , 17 , 18 ]. For instance, a study from late 2020 has showed evidence that SARS-CoV-2 can be detected in EBC by means of RT-qPCR [ 4 , 19 ], prompting an increasing interest towards the use of alternative methods such as lateral flow assays or ELISA technologies [ 5 , 6 ].…”

“…While previous studies have reported highly inconsistent results [ 4 , 13 , 14 , 15 , 16 , 17 , 18 , 21 , 23 , 24 ], there is a substantial lack of evidence on the referral to EBC collection on diagnosis of COVID-19. An updated synthesis of the literature may be therefore useful to healthcare professionals involved in the research of new, non-invasive options for the diagnosis of SARS-CoV-2 infections.…”