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 Malmö, 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.

Flocked nasal swab versus nasopharyngeal aspirate in adult emergency room patients: similar multiplex PCR respiratory pathogen results and patient discomfort.

Fifty adult emergency room patients with symptoms of respiratory tract infections or acute onset of extreme fatigue were sampled by both nasopharyngeal aspirate (NPA) and flocked nasal swab (fNS). Respiratory agents were detected by a qualitative influenza PCR and an 18-valent multiplex PCR in 20 of 29 patients with a clinical diagnosis of respiratory tract infection, and in 3 of 21 without such a diagnosis. PCR detected influenza A and B in NPA samples from 11 patients and in fNS samples from 10 patients. Little or no discomfort was perceived by 60% of the patients when sampled by NPA and by 66% when sampled by fNS. We conclude that NPA and fNS were equally sensitive for detection of respiratory agents by multiplex PCR, and the two sampling methods did not differ significantly regarding discomfort perceived by patients (p = 0.171, Wilcoxon signed rank test). Hence less invasive sampling by fNS might be preferable in certain settings and situations.