Investigation of Clinical Relevance of Bacterial Colonization in Patients With Suspected Viral Respiratory Tract Infection By Using Multiplex PCR Method

Numerous viral and bacterial pathogens have been reported causing acute respiratory tract infection (ARTI). Nasopharyngeal swab (NPS) specimens from 351 patients (278 children, 73 adults) with suspected upper and lower ARTI were submitted during the study period from Jan. 2005 to Dec. 2006. Organism-specific nucleic acids were detected using TemPlex technology (ResPlex I and II, Genaco Biomedical Products, Huntsville, AL). Amplified products were identified using a suspension array for multiplex detection performed on a Luminex 100 instrument (Luminex, Austin, TX). A total of 221 viral and bacterial respiratory agents were detected in 148 patients (135 [48.5%] of the 278 children and 13 [17.8%] of the 73 adults) with suspected ARTI. A single respiratory pathogen was detected in 89 patients [25.35%], whereas mixed infection with two or three pathogens was found in 59 [16.8%] of 351 suspected patients. S. pneumonia was the most frequently isolated strain (54 [15.3%] of 351 patients), followed by H. influenzae (37 [10.5%]), rhinoviruses (35 [9.9%]), influenza A virus (23 [6.5%]), enteroviruses (19 [5.4%]), hMPV (14 [3.9%]), PIV-1 (12 [3.4%]), PIV-3 (11 [3.1%]), RSV (10 [2.8%]), and influenza B virus (6 [1.7%]). Mixed infections were more frequent in children (56 [20.1%] of 278) than adult patients (3 [4.1%] of 73 patients). The detection rate of the bacteria peaked in the spring season (37 [40.6%] of 91 bacteria), followed by winter (24 infections), autumn (18 infections) and summer (12 infections). The prevalence of co-infection is ~40%, finding a much higher incidence of co-infection with more than one agent than that reported previously.