title: Association between early bacterial carriage and otitis media in Aboriginal and non-Aboriginal children in a semi-arid area of Western Australia: a cohort study.
abstract: BACKGROUND
  Streptococcus pneumoniae (Pnc), nontypeable Haemophilus influenzae (NTHi) and Moraxella catarrhalis (Mcat) are the most important bacterial pathogens associated with otitis media (OM). Previous studies have suggested that early upper respiratory tract (URT) bacterial carriage may increase risk of subsequent OM. We investigated associations between early onset of URT bacterial carriage and subsequent diagnosis of OM in Aboriginal and non-Aboriginal children living in the Kalgoorlie-Boulder region located in a semi-arid zone of Western Australia.
  
  
  METHODS
  Aboriginal and non-Aboriginal children who had nasopharyngeal aspirates collected at age 1- < 3 months and at least one clinical examination for OM by an ear, nose and throat specialist before age 2 years were included in this analysis. Tympanometry to detect middle ear effusion was also performed at 2- to 6-monthly scheduled field visits from age 3 months. Multivariate regression models were used to investigate the relationship between early carriage and subsequent diagnosis of OM controlling for environmental factors.
  
  
  RESULTS
  Carriage rates of Pnc, NTHi and Mcat at age 1- < 3 months were 45%, 29% and 48%, respectively, in 66 Aboriginal children and 14%, 5% and 18% in 146 non-Aboriginal children. OM was diagnosed at least once in 71% of Aboriginal children and 43% of non-Aboriginal children. After controlling for age, sex, presence of other bacteria and environmental factors, early nasopharyngeal carriage of NTHi increased the risk of subsequent OM (odds ratio = 3.70, 95% CI 1.22-11.23) in Aboriginal children, while Mcat increased the risk of OM in non-Aboriginal children (odds ratio = 2.63, 95% CI 1.32-5.23). Early carriage of Pnc was not associated with increased risk of OM.
  
  
  CONCLUSIONS
  Early NTHi carriage in Aboriginal children and Mcat in non-Aboriginal children is associated with increased risk of OM independent of environmental factors. In addition to addressing environmental risk factors for carriage such as overcrowding and exposure to environmental tobacco smoke, early administration of pneumococcal-Haemophilus influenzae D protein conjugate vaccine to reduce bacterial carriage in infants, may be beneficial for Aboriginal children; such an approach is currently being evaluated in Australia.
authors.affiliation: Division of Population Sciences, Telethon Institute for Child Health Research, Centre for Child Health Research, The University of Western Australia, PO Box 855, West Perth, WA 6872, Australia.
authors.forename: Wenxing
authors.initials: W
authors.lastname: Sun
authors.forename: Peter
authors.initials: P
authors.lastname: Jacoby
authors.forename: Thomas V
authors.initials: TV
authors.lastname: Riley
authors.forename: Jacinta
authors.initials: J
authors.lastname: Bowman
authors.forename: Amanda Jane
authors.initials: AJ
authors.lastname: Leach
authors.forename: Harvey
authors.initials: H
authors.lastname: Coates
authors.forename: Sharon
authors.initials: S
authors.lastname: Weeks
authors.forename: Allan
authors.initials: A
authors.lastname: Cripps
authors.forename: Deborah
authors.initials: D
authors.lastname: Lehmann
mesh_terms: D002675:Child, Preschool; D005260:Female; D006193:Haemophilus influenzae / Q000472:pathogenicity; D006801:Humans; D007223:Infant; D008297:Male; D001936:Moraxella catarrhalis / Q000472:pathogenicity; D010033:Otitis Media / Q000382:microbiology*; D013296:Streptococcus pneumoniae / Q000472:pathogenicity; D014904:Western Australia