Detection of multiple respiratory viruses by real-time polymerase chain reaction in infants attending an outpatient clinic

Abstract

The detection of respiratory viruses in many prospective clinical studies has relied upon detection with standard laboratory assays, such as antigen detection, viral culture, or serology. Data describing the relative importance of community-acquired respiratory viruses, such as rhinovirus, human metapneumovirus (HMPV) [1], and newly described human coronavirus (HCV) subtypes [2], which are not detectable by these standard assays, in healthy young children who are not admitted to the hospital is limited. We developed a novel respiratory real-time reverse transcription (RT) polymerase chain reaction (PCR) panel to detect the presence of HMPV, respiratory syncytial virus (RSV), influenza viruses A and B, parainfluenza virus (PIV) 1, 2, and 3, adenovirus, human coronaviruses Group 1 (229E and NL63) and Group 2 (OC43 and HKU1), and rhinovirus. We conducted a one-year prospective outpatient community-based study of respiratory tract infections (RTIs) in a healthy infant cohort. Our goals were to determine the proportion of viral RTIs caused by these 13 viruses in symptomatic but otherwise healthy infants, as well as to characterize the clinical features of the identified viral infections and quantify the decline in viral load of patients infected with HMPV in this outpatient population. This cohort surveillance study in a population of healthy infants followed for 13 months was conducted between 1 April 2004 and 1 May 2005. Infants between the ages of 0– 6 months were enrolled from the Well Child Clinic at the Madigan Army Medical Center (MAMC) in Tacoma, WA. All subjects were evaluated at each RTI visit by one of three study physicians. Infections were determined to be lower RTIs if bronchiolitis or pneumonia were diagnosed clinically or radiographically by a study physician. We also assessed the presence of a secondary infection requiring antibiotics. During the 13 months of the study, parents called for an appointment in our study clinic if their infant had any respiratory tract symptoms. The clinical data obtained at the study visits for RTIs and by phone follow-up included the duration and complications of the illness, and missed days of work or daycare. Those infants with new onset of at least 2 of 5 respiratory tract symptoms (cough, rhinorrhea, wheezing, fever, and nasal congestion) had a physical Eur J Clin Microbiol Infect Dis (2008) 27:1245–1248 DOI 10.1007/s10096-008-0558-7