title: Viruses and atypical bacteria associated with asthma exacerbations in hospitalized children.
abstract: OBJECTIVES AND WORKING HYPOTHESIS: To evaluate the prevalence of respiratory viruses Mycoplasma pneumoniae and Chlamydophila pneumoniae and gain insight into their seasonal circulation pattern in children with acute asthma exacerbations in a temperate southern hemisphere region.
  
  
  METHODS
  Patients hospitalized between 3 months and 16 years of age were included in a 1-year prospective, observational, cross-sectional study. Respiratory secretions were collected and the presence of different viruses and atypical bacteria analyzed by immunofluorescence and polymerase chain reaction.
  
  
  RESULTS
  Two hundred nine patients (118 females) aged (mean +/- SD) 4.4 +/- 4 years were included. A potential causative agent was detected in 78% of the patients. The most frequently detected viruses were respiratory syncytial virus (HRSV) (n = 85; 40%) and rhinovirus (HRV) (n = 52; 24.5%); M. pneumoniae and C. pneumoniae were detected in 4.5% and 2% of the cases, respectively. Patients with HRSV (vs. HRV) were hospitalized for a longer time (6.7 vs. 5.2 days, P = 0.012), required more days of oxygen supply (5.1 vs. 3.4, P = 0.005), had a longer duration of the exacerbation before hospitalization (3.6 vs. 1.9 days, P = 0.001) and were younger (3.7 vs. 5.1 years, P = 0.012). Three peaks of admissions were observed. A first peak (early autumn) caused by HRV, a second peak (winter) caused mainly by HRSV and a third one (spring), caused by HRSV, an increase in HMPV together with a second outbreak of HRV.
  
  
  CONCLUSIONS
  Children with an acute asthma exacerbation presented a high prevalence of respiratory viruses. Most hospitalizations corresponded to seasonal increases in prevalence of HRV and HRSV.
authors.affiliation: Centro Respiratorio, Hospital de Niños "Ricardo Gutiérrez," Buenos Aires, Argentina. amaffey@gmail.com
authors.forename: Alberto F
authors.initials: AF
authors.lastname: Maffey
authors.forename: Paola R
authors.initials: PR
authors.lastname: Barrero
authors.forename: Carolina
authors.initials: C
authors.lastname: Venialgo
authors.forename: Francisco
authors.initials: F
authors.lastname: Fernández
authors.forename: Valentina A
authors.initials: VA
authors.lastname: Fuse
authors.forename: Mariana
authors.initials: M
authors.lastname: Saia
authors.forename: Analía
authors.initials: A
authors.lastname: Villalba
authors.forename: Marcelo Rodríguez
authors.initials: MR
authors.lastname: Fermepin
authors.forename: Alejandro M
authors.initials: AM
authors.lastname: Teper
authors.forename: Alicia S
authors.initials: AS
authors.lastname: Mistchenko
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000382:microbiology* / Q000473:pathology* / Q000821:virology; D002648:Child; D002675:Child, Preschool; D023521:Chlamydophila Infections / Q000150:complications / Q000175:diagnosis; D016993:Chlamydophila pneumoniae / Q000302:isolation & purification; D003430:Cross-Sectional Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D007223:Infant; D007902:Length of Stay; D008297:Male; D009177:Mycoplasma pneumoniae / Q000302:isolation & purification; D010102:Oxygen Inhalation Therapy; D010850:Picornaviridae Infections / Q000150:complications / Q000175:diagnosis; D011019:Pneumonia, Mycoplasma / Q000150:complications / Q000175:diagnosis; D011446:Prospective Studies; D018357:Respiratory Syncytial Virus Infections / Q000150:complications / Q000175:diagnosis; D012621:Seasons; D013183:Sputum / Q000382:microbiology / Q000821:virology