A combination of naso- and oropharyngeal swabs improves the diagnostic yield of respiratory viruses in adult emergency department patients

Background: Along with the current development of molecular diagnostic methods of respiratory viruses, the bedside patient sampling techniques need to be evaluated. We here asked the question whether the addition of an oropharynx swab to the traditional nasopharynx swab might improve the diagnostic yield of multiplex PCR analysis. Ct values from the two sampling sites were compared as well as patient tolerability. Methods: In an emergency department in Malmo, Sweden, 98 adult patients with respiratory disease were sampled both from the nasopharynx and oropharynx for virus diagnostics by PCR. Results: Influenza (AH1, AH3, B), human metapneumovirus (hMPV) or respiratory syncytial virus (RSV) were detected by PCR in 58 subjects. The diagnostic yield was improved by combining nasopharyngeal and oropharyngeal sampling - a virus was detected in another 6 patients compared to traditional nasopharyngeal sampling (p = .031, McNemar's test). In 38/55 subjects viral load was higher in the nasopharynx than in the oropharynx. Self-reported discomfort was significantly lower from oropharyngeal sampling than from nasopharyngeal sampling. Conclusions: Adding an oropharynx sample to a nasopharynx sample increased the diagnostic yield of respiratory viruses. Oropharyngeal sampling was well tolerated.