Comparison of throat swabs and sputum specimens for viral nucleic acid detection in 52 cases of novel coronavirus (SARS-Cov-2)-infected pneumonia (COVID-19).
Author(s): Lin C, Xiang J, Yan M, Li H, Huang S, Shen C
Publication: Clin Chem Lab Med, 2020, Vol. , Page
PubMed ID: 32301745 PubMed Review Paper? No
Purpose of Paper
This paper compared the detection of SARS-CoV-2, the virus that causes the novel 2019 coronavirus disease (COVID, COVID-19, COVID19) by real-time RT- PCR in matched oropharyngeal swab and sputum specimens.
Conclusion of Paper
Almost twice as many sputum specimens as oropharyngeal swab specimens were positive for SARS-CoV-2 viral RNA. Results were concordant between specimen types for 51.9% of patients (36.5% positive in both specimens and 15.4% negative in both specimens).
Studies
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Study Purpose
This study compared the detection of SARS-CoV-2 RNA by real-time RT- PCR in matched oropharyngeal swab and sputum specimens. Matched oropharyngeal swab and sputum specimens were collected from 52 patients suspected of having COVID-19. Oropharyngeal specimens were collected with a nylon-flocked swab (avoiding the tongue) and immediately placed into a tube containing 2-3 mL of sterile saline. To collect sputum, patients were asked to cough up deep sputum from the lower airways and the specimen was collected in sterile tubes. Sputum specimens were microscopically screened for squamous epithelial cells (SECs) and polymorphonuclear cells (PMNs), with <10 SECs and >25 PMNs per low-power field regarded as high quality. To fully liquefy the sputum, an equal volume of acetylcysteine (10 g/L) was added and the specimen was shaken at room temperature for 30 min. Viral RNA was extracted using the QIAamp Viral RNA Mini Kit and SARS-CoV-2 was detected using a 2019-nCoV nucleic acid real-time RT-PCR detection kit.
Summary of Findings:
Almost twice as many sputum specimens as oropharyngeal swab specimens were positive for SARS-CoV-2 viral RNA (44.2% versus 76.9%, P=0.001). Results were concordant between specimen types for 51.9% of patients with 36.5% of patients having positive in both specimens and 15.4% of patients negative in both specimens. However, 40.4% patients had positive sputum specimens and negative oropharyngeal swab specimens while only 7.7% had negative sputum specimens and positive oropharyngeal swab specimens.
Biospecimens
Preservative Types
- None (Fresh)
Diagnoses:
- Pneumonia/Respiratory Infection
Platform:
Analyte Technology Platform RNA Real-time qRT-PCR Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Real-time qRT-PCR Specific Targeted nucleic acid 2019-nCoV RNA
Biospecimen Acquisition Biospecimen location Oropharynx
Sputum