title: Rapid detection of respiratory viruses by centrifugation enhanced cultures from children with acute lower respiratory tract infections.
abstract: BACKGROUND
  Acute respiratory tract infection (ARI) is the major cause of morbidity and mortality in young children in developing countries. Information on viral aetiology in ARI in India is very limited.
  
  
  OBJECTIVE
  The aim of the study was to define the role of viruses in acute lower respiratory tract infections (ALRTI) in children in India using centrifugation enhanced cultures followed by indirect immunofluorescence (IIF).
  
  
  METHODS
  Nasopharyngeal aspirates (NPAs) were collected from children from September 1995 to April 1997, attending paediatric clinic of All India Institute of Medical Sciences (AIIMS) with symptoms of ALRTI. Virus isolation was done by centrifugation enhanced cultures using HEp-2, LLC-MK2 and MDCK cells. The viruses were identified at 24-48 h post inoculation by IIF staining using monoclonal antibodies to respiratory syncytial virus (RSV), parainfluenza virus (PIV), influenza virus and adenovirus.
  
  
  RESULTS
  Of 200 NPA samples, 89 (44.5%) were positive for one or more viral pathogens. RSV was detected in 34 (17%) of all ALRTI cases followed by influenza viruses in 29 (14.5%), PIVs in 23 (11.5%) and adenoviruses in three (1.5%). In 79 children with bronchiolitis, RSV was most frequently isolated (25%) pathogen, while in bronchopneumonia cases (101) the most common viral pathogen was influenza virus (17%). In eight cases (4%) of ALRTI dual infections were detected. In 100 NPA specimens IIF staining on direct cell smears was carried out and viruses were detected in only 17%. RSV and influenza virus infection peaked from September to December, where as PIV infections were more frequent from January to April.
  
  
  CONCLUSIONS
  Respiratory viruses accounted for 44.5% of cases of ALRTI in India and the results of viral aetiology could be given in 24-48 h using centrifugation enhanced cultures. RSV was the most common viral agent associated with ALRTI in children under 5 years of age with greater association with bronchiolitis.
authors.affiliation: Department of Microbiology, All India Institute of Medical Sciences, New Delhi.
authors.forename: R S
authors.initials: RS
authors.lastname: Maitreyi
authors.forename: S
authors.initials: S
authors.lastname: Broor
authors.forename: S K
authors.initials: SK
authors.lastname: Kabra
authors.forename: M
authors.initials: M
authors.lastname: Ghosh
authors.forename: P
authors.initials: P
authors.lastname: Seth
authors.forename: L
authors.initials: L
authors.lastname: Dar
authors.forename: A K
authors.initials: AK
authors.lastname: Prasad
mesh_terms: D000260:Adenoviruses, Human / Q000302:isolation & purification*; D002498:Centrifugation; D002675:Child, Preschool; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D009305:Nasopharynx / Q000821:virology; D009975:Orthomyxoviridae / Q000302:isolation & purification*; D018184:Paramyxoviridae Infections / Q000821:virology*; D012136:Respiratory Syncytial Viruses / Q000302:isolation & purification*; D012141:Respiratory Tract Infections / Q000821:virology*; D014776:Virus Cultivation; D014777:Virus Diseases / Q000821:virology