Detection of SARS-CoV-2 Infection in Gargle, Spit, and Sputum Specimens

ABSTRACT The gold standard for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection diagnosis is reverse transcription (RT)-PCR from a nasopharyngeal swab specimen (NPS). Its collection involves close contact between patients and health care workers, requiring a significant amount...

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Main Authors: Eero Poukka, Henna Mäkelä, Lotta Hagberg, Thuan Vo, Hanna Nohynek, Niina Ikonen, Kirsi Liitsola, Otto Helve, Carita Savolainen-Kopra, Timothée Dub
Format: Article
Language:English
Published: American Society for Microbiology 2021-09-01
Series:Microbiology Spectrum
Subjects:
Online Access:https://journals.asm.org/doi/10.1128/Spectrum.00035-21
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author Eero Poukka
Henna Mäkelä
Lotta Hagberg
Thuan Vo
Hanna Nohynek
Niina Ikonen
Kirsi Liitsola
Otto Helve
Carita Savolainen-Kopra
Timothée Dub
author_facet Eero Poukka
Henna Mäkelä
Lotta Hagberg
Thuan Vo
Hanna Nohynek
Niina Ikonen
Kirsi Liitsola
Otto Helve
Carita Savolainen-Kopra
Timothée Dub
author_sort Eero Poukka
collection DOAJ
description ABSTRACT The gold standard for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection diagnosis is reverse transcription (RT)-PCR from a nasopharyngeal swab specimen (NPS). Its collection involves close contact between patients and health care workers, requiring a significant amount of workforce and putting them at risk of infection. We evaluated self-collection of alternative specimens and compared their sensitivity and cycle threshold (CT) values to those of NPS. We visited acute coronavirus disease 2019 (COVID-19) outpatients to collect concomitant NPS and gargle specimens and had patients self-collect gargle and either sputum or spit specimens the next morning. We included 40 patients and collected 40 concomitant NPS and gargle specimens, as well as 40 gargle, 22 spit, and 16 sputum specimens the next day (2 patients could not produce sputum). All specimens were as sensitive as NPS. Gargle specimens had a sensitivity of 0.97 (95% confidence interval [CI], 0.92 to 1.00), whether collected concomitantly with NPS or the next morning. Next-morning spit and sputum specimens showed sensitivities of 1.00 (95% CI, 1.00 to 1.00) and 0.94 (95% CI, 0.87 to 1.00]), respectively. The gargle specimens had significantly higher mean CT values of 29.89 (standard deviation [SD], 4.63; P < 0.001) and 29.25 (SD, 3.99; P < 0.001) when collected concomitantly and the next morning, respectively, compared to NPS (22.07 [SD, 4.63]). CT values obtained with spit (23.51 [SD, 4.57]; P = 0.11) and sputum (25.82 [SD, 9.21]; P = 0.28) specimens were close to those of NPS. All alternative specimen collection methods were as sensitive as NPS, but spit collection appeared more promising, with a low CT value and ease of collection. Our findings warrant further investigation. IMPORTANCE Control of the COVID-19 pandemic relies heavily on a test-trace-isolate strategy. The most commonly used specimen for diagnosis of SARS-CoV-2 infection is a nasopharyngeal swab. However, this method is quite uncomfortable for the patient, requires specific equipment (nose swabs and containers), and requires close proximity to health care workers, putting them at risk of infection. Developing alternative sampling strategies could decrease the burden for health care workers, help overcome potential shortages of equipment, and improve acceptability of testing by reducing patient discomfort.
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spelling doaj.art-af5e7f3f788e4767bf3b3b9de0f23bb12022-12-21T21:19:21ZengAmerican Society for MicrobiologyMicrobiology Spectrum2165-04972021-09-019110.1128/Spectrum.00035-21Detection of SARS-CoV-2 Infection in Gargle, Spit, and Sputum SpecimensEero Poukka0Henna Mäkelä1Lotta Hagberg2Thuan Vo3Hanna Nohynek4Niina Ikonen5Kirsi Liitsola6Otto Helve7Carita Savolainen-Kopra8Timothée Dub9Infectious Disease Control and Vaccinations Unit, Department of Health Security, Finnish Institute for Health and Welfare, Helsinki, FinlandInfectious Disease Control and Vaccinations Unit, Department of Health Security, Finnish Institute for Health and Welfare, Helsinki, FinlandExpert Microbiology Unit, Department of Health Security, Finnish Institute for Health and Welfare, Helsinki, FinlandInfectious Disease Control and Vaccinations Unit, Department of Health Security, Finnish Institute for Health and Welfare, Helsinki, FinlandInfectious Disease Control and Vaccinations Unit, Department of Health Security, Finnish Institute for Health and Welfare, Helsinki, FinlandExpert Microbiology Unit, Department of Health Security, Finnish Institute for Health and Welfare, Helsinki, FinlandExpert Microbiology Unit, Department of Health Security, Finnish Institute for Health and Welfare, Helsinki, FinlandInfectious Disease Control and Vaccinations Unit, Department of Health Security, Finnish Institute for Health and Welfare, Helsinki, FinlandExpert Microbiology Unit, Department of Health Security, Finnish Institute for Health and Welfare, Helsinki, FinlandInfectious Disease Control and Vaccinations Unit, Department of Health Security, Finnish Institute for Health and Welfare, Helsinki, FinlandABSTRACT The gold standard for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection diagnosis is reverse transcription (RT)-PCR from a nasopharyngeal swab specimen (NPS). Its collection involves close contact between patients and health care workers, requiring a significant amount of workforce and putting them at risk of infection. We evaluated self-collection of alternative specimens and compared their sensitivity and cycle threshold (CT) values to those of NPS. We visited acute coronavirus disease 2019 (COVID-19) outpatients to collect concomitant NPS and gargle specimens and had patients self-collect gargle and either sputum or spit specimens the next morning. We included 40 patients and collected 40 concomitant NPS and gargle specimens, as well as 40 gargle, 22 spit, and 16 sputum specimens the next day (2 patients could not produce sputum). All specimens were as sensitive as NPS. Gargle specimens had a sensitivity of 0.97 (95% confidence interval [CI], 0.92 to 1.00), whether collected concomitantly with NPS or the next morning. Next-morning spit and sputum specimens showed sensitivities of 1.00 (95% CI, 1.00 to 1.00) and 0.94 (95% CI, 0.87 to 1.00]), respectively. The gargle specimens had significantly higher mean CT values of 29.89 (standard deviation [SD], 4.63; P < 0.001) and 29.25 (SD, 3.99; P < 0.001) when collected concomitantly and the next morning, respectively, compared to NPS (22.07 [SD, 4.63]). CT values obtained with spit (23.51 [SD, 4.57]; P = 0.11) and sputum (25.82 [SD, 9.21]; P = 0.28) specimens were close to those of NPS. All alternative specimen collection methods were as sensitive as NPS, but spit collection appeared more promising, with a low CT value and ease of collection. Our findings warrant further investigation. IMPORTANCE Control of the COVID-19 pandemic relies heavily on a test-trace-isolate strategy. The most commonly used specimen for diagnosis of SARS-CoV-2 infection is a nasopharyngeal swab. However, this method is quite uncomfortable for the patient, requires specific equipment (nose swabs and containers), and requires close proximity to health care workers, putting them at risk of infection. Developing alternative sampling strategies could decrease the burden for health care workers, help overcome potential shortages of equipment, and improve acceptability of testing by reducing patient discomfort.https://journals.asm.org/doi/10.1128/Spectrum.00035-21alternative testing methodsCOVID-19garglenasopharyngeal swabSARS-CoV-2spit
spellingShingle Eero Poukka
Henna Mäkelä
Lotta Hagberg
Thuan Vo
Hanna Nohynek
Niina Ikonen
Kirsi Liitsola
Otto Helve
Carita Savolainen-Kopra
Timothée Dub
Detection of SARS-CoV-2 Infection in Gargle, Spit, and Sputum Specimens
Microbiology Spectrum
alternative testing methods
COVID-19
gargle
nasopharyngeal swab
SARS-CoV-2
spit
title Detection of SARS-CoV-2 Infection in Gargle, Spit, and Sputum Specimens
title_full Detection of SARS-CoV-2 Infection in Gargle, Spit, and Sputum Specimens
title_fullStr Detection of SARS-CoV-2 Infection in Gargle, Spit, and Sputum Specimens
title_full_unstemmed Detection of SARS-CoV-2 Infection in Gargle, Spit, and Sputum Specimens
title_short Detection of SARS-CoV-2 Infection in Gargle, Spit, and Sputum Specimens
title_sort detection of sars cov 2 infection in gargle spit and sputum specimens
topic alternative testing methods
COVID-19
gargle
nasopharyngeal swab
SARS-CoV-2
spit
url https://journals.asm.org/doi/10.1128/Spectrum.00035-21
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