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.