Upper respiratory tract bacterial carriage in Aboriginal and non-Aboriginal children in a semi-arid area of Western Australia

Background: Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis are associated with otitis media (OM). Indigenous children experience particularly high rates of OM. Few studies worldwide have described upper respiratory tract (URT) carriage in Indigenous and non-Indigenous children living in the same area. Aim: The aim of this study was to describe URT bacterial carriage in Aboriginal and non-Aboriginal children in the Kalgoorlie-Boulder area, Western Australia, as part of an investigation into causal pathways to OM. Methods: Five hundred four and 1045 nasopharyngeal aspirates were collected from 100 Aboriginal and 180 non-Aboriginal children, respectively, followed from birth to age 2 years. Standard procedures were used to identify bacteria. Results: Overall carriage rates of S. pneumoniae, M. catarrhalis and H. influenzae in Aboriginal children were 49%, 50% and 41%, respectively, and 25%, 25% and 11% in non-Aboriginal children. By age 2 months S. pneumoniae and M. catarrhalis had been isolated from 37% and 36% of Aboriginal children and from 11% and 12% of non-Aboriginal children, respectively. From age 3 months onward, carriage rates in Aboriginal children were 51% to 67% for S. pneumoniae and M. catarrhalis and 42% to 62% for H. influenzae; corresponding figures for non-Aboriginal children were 26% to 37% for S. pneumoniae and M. catarrhalis and 11% to 18% for H. influenzae. Non-Aboriginal children had higher carriage rates in winter than in summer, but season had little effect in Aboriginal children. Staphylococcus aureus carriage was highest under age 1 month (55% Aboriginal, 61% non-Aboriginal) and was always higher in non-Aboriginal than Aboriginal children. Conclusions: Interventions are needed to reduce high transmission and carriage rates, particularly in Aboriginal communities, to avoid the serious consequences of OM.