To investigate the correlation between the detection rate of respiratory viral pathogens with automated nested multiplex PCR system and the infectious indexes such as peripheral white blood cell (WBC), lymphocyte percentage (LYN%) and C-reactive protein (CRP), retrospectively.

From November 2016 to December 2017, a total of 103 nasopharyngeal swabs and clinical data from patients with respiratory infection were collected in Beijing Ditan Hospital, Capital Medical University. The pathogens were detected by automated nested multiplex PCR system, and the results was statistically analyzed.

The rate of detection among 103 nasopharyngeal swabs was 62.14% (64/103), and influenza virus had the highest positive rate of 26.21% (27/103). Compared with the virus detected group, the number of patients with cough was significantly larger (χ² = 12.898, P < 0.001), the period was shorter (t =-2.727, P = 0.008), and the CRP level was lower (t =-1.897, P = 0.016), with significant differences. Patients were divided into three groups according to C-reactive protein value: ≤ 10 mg/L group, 10-50 mg/L group and > 50 mg/L group; the virus detection rate among groups with different CRP levels was significantly different (χ² = 10.448, P = 0.005), and the highest detection rate was 77.50% (31/40) for the group with CRP ≤ 10 mg/L. The analysis of the subjects’ working characteristics curve (ROC) showed that the area of WBC, LYN% and CRP under the curve were 0.565, 0.593 and 0.678, respectively. When the Cut-off value of CRP was 18.2 mg/L, the sensitivity and specificity were 73.3% and 64.2%, respectively.

Automated nested multiplex PCR system could identify multiple viral respiratory pathogens in short period. When patients with respiratory tract infection characterized by cough and fever in the early stage, or levels of WBC, LYN% and CRP were not high, respiratory tract viral infection may be detected, clinicians could furtherly choose automated nested multiplex PCR system to identify the pathogen.