ABSTRACT
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) initially infects and replicates in epithelial cells of the nasopharynx where there are relatively high levels of angiotensin-converting enzyme 2 receptor, which correlates with the highest sensitivity time point of the nasopharyngeal swab (NPS) real-time polymerase chain reaction (RT-PCR) during the first week, with subsequent decline thereafter. As viral shedding progresses throughout the respiratory tract, the virus can be detectable for up to 30 days in bronchoalveolar fluids. This report presents three cases of acute respiratory distress in the setting of multifocal pneumonia, with multiple false-negative NPS SARS-CoV-2/RT-PCR but positive SARS-CoV-2/RT-PCR in bronchoalveolar lavage (BAL) samples. Molecular RT-PCR testing remains the gold standard in the diagnosis of SARS-CoV-2 infection. However, the diagnostic accuracy of NPS RT-PCR may be affected by several factors. SARS-CoV-2/RT-PCR in BAL samples increases the diagnostic yield for coronavirus disease 2019 pneumonia; however, it is not widely available in many institutions and can be clinically challenging to perform. A multimodal approach is required for prompt diagnosis, especially in patients with a progressive disease, where a delay in therapy can be clinically detrimental.
