Comparison among Nasopharyngeal Swab, Nasal Wash and Oropharyngeal Swab for Respiratory Viruses Detection in Adults with Acute Pharyngitis

Background: Acute pharyngitis is one of the most common illnesses for which patients visit primary care physicians. Its etiology is primarily viral in adults. Only about 10% of cases have a bacterial cause. Nonetheless, a total of 78-98% of adults with acute pharyngitis was treated with antibiotics. Thus, virological investigation prior to treating would support the appropriate use of antiviral therapy and reduced the inappropriate use of antibiotics for patients. The purpose of this study was to compare the sensitivities and rates of viral detection among oropharyngeal swab (OPS), nasopharyngeal swab (NPS) and nasal wash (NW) in adults with acute pharyngitis. Methods: OPS, NPS and NW were obtained from each participant with acute pharyngitis. The specimens were tested for 15 respiratory viruses by Taqman real-time polymerase chain reaction. A sample was considered a true positive if any of the specimens was positive. The sensitivities and detection rates between samples were compared by the Chi-square test or Fisher’s exact test, as appropriate. Result: 103 triple samples collected with OPS, NPS and NW consecutively were obtained. 73 patients had at least one virus detected from any of the three methods. The detection rates for any virus were 81% (NPS), 52% (NW), and 60% (OPS). And the detection rates for any virus in NPS were significant higher than that in NW (p<0.01) and OPS (p<0.01) respectively. In detection of all viruses, the sensitivity of NPS was significantly higher than NW (74% vs. 49%, p<0.01) and OPS(74% vs. 49%, p<0.01) respectively. Conclusions: We concluded the NPS collection was the best cost-utility sampling method in adults with acute pharyngitis.