title: Nitric oxide metabolites as biomarkers for influenza-like acute respiratory infections presenting to the emergency room.
abstract: OBJECTIVE
  Nitric oxide (NO) is increased in the respiratory tract in pulmonary infections. The aim was to determine whether nasal wash NO metabolites could serve as biomarkers of viral pathogen and disease severity in children with influenza-like illness (ILI) presenting to the emergency department (ED) during the 2009 influenza A H1N1 pandemic.
  
  
  METHODS
  Children ≤18 years old presenting to the ED with ILI were eligible. Nasal wash specimens were tested for NO metabolites, nitrate and nitrite, by HPLC and for respiratory viruses by real-time PCR.
  
  
  RESULTS
  Eighty-nine patients with ILI were prospectively enrolled during Oct-Dec, 2009. In the entire cohort, nasal wash nitrite was low to undetectable (interquartile range [IQR], 0 - 2 μM), while median nitrate was 3.4 μM (IQR 0-8.6). Rhinovirus (23%), respiratory syncytial virus (RSV) (20%), novel H1N1 (19%), and adenovirus (11%) were the most common viruses found. Children with RSV subtype B-associated ILI had higher nitrate compared to all other viruses combined (P=0.002).
  
  
  CONCLUSIONS
  Concentration of NO-derived nitrate in nasal secretions in children in the ED is suggestive of viral pathogen causative for ILI, and thus might be of clinical utility. Predictive potential of this putative biomarker for ILI needs further evaluation in sicker patients in a prospective manner.
authors.affiliation: Dept of Pediatrics, Section of Emergency Medicine, Texas Children's Hospital, Baylor College of Medicine, Houston TX 77030, USA.
authors.forename: Asad I
authors.initials: AI
authors.lastname: Mian
authors.forename: Federico R
authors.initials: FR
authors.lastname: Laham
authors.forename: Andrea T
authors.initials: AT
authors.lastname: Cruz
authors.forename: Harsha
authors.initials: H
authors.lastname: Garg
authors.forename: Charles G
authors.initials: CG
authors.lastname: Macias
authors.forename: A Chantal
authors.initials: AC
authors.lastname: Caviness
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Piedra