Detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in upper and lower respiratory specimens and coinfection with other respiratory pathogens in patients with coronavirus disease 2019 (COVID-19) were investigated. From the study subjects (N = 258) retrospectively enrolled when confirmed as SARS-CoV-2 positive, nasopharyngeal (NPS), oropharyngeal swabs (OPS), and sputum specimens were restored for retesting SARS-CoV-2 and detecting respiratory pathogens. Majority of the study subjects (95.7%, N = 247) were confirmed as SARS-CoV-2 positive using NPS/OPS specimens, suggesting that the upper respiratory specimen is most valuable in detecting SARS-CoV-2. Coinfection rates in COVID-19 patients (N = 258) with respiratory pathogens were 9.7% (N = 25); 8.5% (N = 22) respiratory viruses and 1.2% (N = 3) Mycoplasma pneumoniae, an atypical bacterium. Of the respiratory virus coinfection cases (N = 22), 20 (90.9%) were co-infected with a single respiratory virus and 2 (0.8%) (metapneumovirus/adenovirus and rhinovirus/bocavirus 1/2/3/4) with two viruses. Respiratory viruses in single viral coinfection cases with SARS-CoV-2 were as follows: non-SARS-CoV-2 coronaviruses (229E, NL63, and OC43, N = 5, 1.9%), rhinovirus (N = 4, 1.6%), metapneumovirus (N = 3, 1.2%), influenza A (N = 3, 1.2%), respiratory syncytial virus A and B (N = 3, 1.2%), and adenovirus (N = 2, 0.8%). No mixed coinfections with respiratory viruses and M. pneumoniae were found. In conclusion, the diagnostic value of utilizing NPS/OPS specimen is excellent, and, as the first report in Korea, coinfection with respiratory pathogens were detected at a rate of 9.7% in patients with COVID-19.
