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Are two consecutive negative RT-PCR results enough to rule out COVID-19?
R Waked1, J Makhoul1, G Saliba1
1Department of Infectious Diseases, Faculty of Medicine, Saint Joseph University, Beirut, Lebanon.
New Microbes and New Infections
|September 3, 2020
Summary
Deep sampling RT-PCR of lower respiratory tract secretions is crucial for diagnosing COVID-19 when initial upper respiratory tests are negative. This enhances severe acute respiratory syndrome coronavirus 2 detection sensitivity.
Area of Science:
- Infectious Diseases
- Respiratory Medicine
- Diagnostic Microbiology
Background:
- The COVID-19 pandemic necessitates accurate and timely diagnosis of SARS-CoV-2 infections.
- Real-time reverse transcription PCR (RT-PCR) is the standard diagnostic method for SARS-CoV-2.
- Current RT-PCR protocols often rely on upper respiratory tract samples.
Observation:
- A patient with high clinical suspicion for COVID-19 presented with fever and bilateral pneumonia.
- Initial nasopharyngeal swab RT-PCR tests for SARS-CoV-2 were negative.
- A subsequent bronchoscopy with bronchoalveolar lavage (BAL) allowed for deep sampling.
Findings:
- RT-PCR testing of BAL samples yielded a positive result for SARS-CoV-2, confirming COVID-19 pneumonia.
- Lower respiratory tract samples appear to harbor a higher viral load compared to upper respiratory samples.
- Deep sampling via bronchoscopy significantly increased diagnostic sensitivity in this case.
Implications:
- RT-PCR testing of lower respiratory tract samples should be considered in cases with high clinical suspicion but negative upper respiratory testing.
- Optimizing diagnostic strategies is essential for effective COVID-19 management and control.
- This approach may improve the detection rates of SARS-CoV-2, particularly in hospitalized patients with pneumonia.
