Importance Of Lower Respiratory Tract Samples For Diagnosis Of Coronavirus Disease 2019 (Covid-19)

SESSION TITLE: Medical Student/Resident Chest Infections Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Nasopharyngeal (NP) swabs are the most common samples collected for testing of severe acute respiratory syndrome coronavirus-19 (COVID-19). There is a growing concern for false-negative rates, up to 30-50% reported by reverse transcriptase-polymerase chain reaction (rt-PCR) in NP swabs.This case brings about the significance of lower respiratory tract (LRT) samples for COVID-19 testing and the importance of clinical judgment to light. CASE PRESENTATION: A 77-year-old male who tested positive for COVID-19 at a community testing center three days ago presented to the hospital with confusion and weakness.On evaluation, he was confused, hypoxic, requiring three-liter oxygen and had diffuse crackles on auscultation. Work up was pertinent for bibasilar opacities on chest X-ray and a procalcitonin of 0.09. Ceftriaxone and azithromycin were started for empiric treatment of secondary bacterial infection. Computed Tomography (CT), Magnetic Resonance Imaging (MRI) head, and lumbar puncture for evaluation of confusion were negative. His confusion was attributed to COVID induced encephalopathy. His oxygen requirements continued to increase during his hospitalization, and subsequent chest X-rays showed worsening of air space opacities. Procalcitonin was unchanged, and blood cultures were negative. NP swabs from three consecutive days were negative for COVID-19. CT angiography was negative for pulmonary embolism but showed peripheral consolidations with ground glass opacities. He then underwent bronchoscopy with bronchoalveolar lavage (BAL), which was positive for COVID-19. The patient remained intubated after the procedure and could not be weaned off. Palliative care was consulted to discuss goals of care, and the patient eventually succumbed to the infection. DISCUSSION: LRT samples including sputum or BAL should be collected in patients who test negative but have a high suspicion for COVID-19. A study evaluated 866 samples from 213 confirmed patients and showed an almost 100% positive rate in BAL, followed by sputum and nasal swabs. [1] Additionally, the virus can be detected in LRT specimens before the onset of symptoms or X-ray changes, predicting the course of the disease earlier than expected. [2]The virus binds to ACE-2 receptors, the concentration of which is high in alveolar epithelial cells and minimal in nasal, oral, and bronchial epithelial cells. [3]Other factors contributing to false negatives in the NP sample include improper technique of collection, transportation, or lower viral load at the time of testing. CONCLUSIONS: Relying only on NP swabs for diagnosing COVID-19 could lead to under detection and treatment, in turn worsening the disease load by community spread. Since bronchoscopy is needed for collecting BAL, other less invasive techniques like endotracheal aspirate, blinded bronchial sampling, mini BAL can be looked into. Reference #1: Yang Y, Yang M, Shen C, et al. Evaluating the accuracy of different respiratory specimens in the laboratory diagnosis and monitoring the viral shedding of 2019-nCoV infections. 2020; Reference #2: Kim JY, Ko J-H, Kim Y, et al. Viral Load Kinetics of SARS-CoV-2 Infection in First Two Patients in Korea. Journal of Korean Medical Science 2020;35(7). Reference #3: Winichakoon P, Chaiwarith R, Liwsrisakun C, et al. Negative Nasopharyngeal and Oropharyngeal Swabs Do Not Rule Out COVID-19. Journal of Clinical Microbiology 2020;58(5). DISCLOSURES: No relevant relationships by Navdeep Dehal, source=Web Response No relevant relationships by Jeffrey Macaraeg, source=Web Response