Comparison of Throat Washings, Nasopharyngeal Swabs and Oropharyngeal Swabs for Detection of SARS-CoV-2

• Main Authors: Florian Hitzenbichler, Stilla Bauernfeind, Bernd Salzberger, Barbara Schmidt, Jürgen J. Wenzel
• Format: Article
• Language: English
• Published: MDPI AG 2021-04-01
• Series: Viruses
• Subjects: SARS-CoV-2; COVID-19; throat washing; nasopharyngeal swab; oropharyngeal swab; saliva
• Online Access: https://www.mdpi.com/1999-4915/13/4/653

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) RNA is detected by reverse-transcription quantitative real-time PCR (RT-qPCR) from respiratory specimens. This study compares throat washings (TW), nasopharyngeal swabs (NS) and oropharyngeal swabs (OS). A total of 102 samples from 34 adult patients with confirmed SARS-CoV-2 infection were analysed by RT-qPCR with absolute quantification. The median concentrations and diagnostic sensitivities were <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>5</mn><mo>.</mo><mn>8</mn><mo>×</mo><msup><mn>10</mn><mn>4</mn></msup></mrow></semantics></math></inline-formula> copies/mL, 85% (NS), <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1</mn><mo>.</mo><mn>4</mn><mo>×</mo><msup><mn>10</mn><mn>4</mn></msup></mrow></semantics></math></inline-formula>, 79% (OS) and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>4</mn><mo>.</mo><mn>3</mn><mo>×</mo><msup><mn>10</mn><mn>3</mn></msup></mrow></semantics></math></inline-formula>, 85% (TW). Concentration differences were significant between NS and TW (<i>P</i> = 0.019). Saliva (SA) was available from 21 patients (median <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>3</mn><mo>.</mo><mn>4</mn><mo>×</mo><msup><mn>10</mn><mn>3</mn></msup></mrow></semantics></math></inline-formula>). OS and TW can be considered for SARS-CoV-2 diagnostics, although with slightly lower concentrations.