title: Infection with multiple viruses is not associated with increased disease severity in children with bronchiolitis.
abstract: BACKGROUND
  The clinical relevance of parallel detection of multiple viruses by real-time polymerase chain reaction (RT-PCR) remains unclear. This study evaluated the association between the detection of multiple viruses by RT-PCR and disease severity in children with bronchiolitis.
  
  
  METHODS
  Children less than 2 years of age with clinical symptoms of bronchiolitis were prospectively included during three winter seasons. Patients were categorized in three groups based on disease severity; mild (no supportive treatment), moderate (supplemental oxygen and/or nasogastric feeding), and severe (mechanical ventilation). Multiplex RT-PCR of 15 respiratory viruses was performed on nasopharyngeal aspirates.
  
  
  RESULTS
  In total, 142 samples were obtained. Respiratory Syncytial virus (RSV) was the most commonly detected virus (73%) followed by rhinovirus (RV) (30%). In 58 samples (41%) more than one virus was detected, of which 41% was a dual infection with RSV and RV. In RSV infected children younger than 3 months, disease severity was not associated with the number of detected viruses. Remarkably, in children older than 3 months we found an association between more severe disease and RSV mono-infections.
  
  
  CONCLUSIONS
  Disease severity in children with bronchiolitis is not associated with infection by multiple viruses. We conclude that other factors, such as age, contribute to disease severity to a larger extent.
authors: Department of Pediatrics, Radboud University Nijmegen Medical Centre, P.O. box 9101, 6500 HB, Nijmegen, The Netherlands. K.brand@cukz.umcn.nl
authors: H Kim
authors: HK
authors: Brand
authors: Ronald
authors: R
authors: de Groot
authors: Joep M D
authors: JM
authors: Galama
authors: Marianne L
authors: ML
authors: Brouwer
authors: Karin
authors: K
authors: Teuwen
authors: Peter W M
authors: PW
authors: Hermans
authors: Willem J G
authors: WJ
authors: Melchers
authors: Adilia
authors: A
authors: Warris
mesh_terms: D001988:Bronchiolitis / Q000821:virology*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D010850:Picornaviridae Infections / Q000175:diagnosis* / Q000821:virology; D011446:Prospective Studies; D018357:Respiratory Syncytial Virus Infections / Q000175:diagnosis* / Q000821:virology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012229:Rhinovirus / Q000302:isolation & purification; D012720:Severity of Illness Index