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BMC Ear, Nose and Throat Disorders

, 6:10

First Online: 10 May 2006Received: 31 October 2005Accepted: 10 May 2006


BackgroundNasal colonisation with otitis media OM pathogens, particularly Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis, is a precursor to the onset of OM. Many children experience asymptomatic nasal carriage of these pathogens whereas others will progress to otitis media with effusion OME or suppurative OM. We observed a disparity in the prevalence of suppurative OM between Aboriginal children living in remote communities and non-Aboriginal children attending child-care centres; up to 60% and <1%, respectively. This could not be explained by the less dramatic difference in rates of carriage of respiratory bacterial pathogens 80% vs 50%, respectively. In this study, we measured nasal bacterial load to help explain the different propensity for suppurative OM in these two populations.

MethodsQuantitative measures colony counts and real-time quantitative PCR of the respiratory pathogens S. pneumoniae, H. influenzae and M. catarrhalis, and total bacterial load were analysed in nasal swabs from Aboriginal children from remote communities, and non-Aboriginal children attending urban child-care centres.

ResultsIn both populations nearly all swabs were positive for at least one of these respiratory pathogens. Using either quantification method, positive correlations between bacterial load and ear state no OM, OME, or suppurative OM were observed. This relationship held for single and combined bacterial respiratory pathogens, total bacterial load, and the proportion of respiratory pathogens to total bacterial load. Comparison of Aboriginal and non-Aboriginal children, all with a diagnosis of OME, demonstrated significantly higher loads of S. pneumoniae and M. catarrhalis in the Aboriginal group. The increased bacterial load despite similar clinical condition may predict persistence of middle ear effusions and progression to suppurative OM in the Aboriginal population. Our data also demonstrated the presence of PCR-detectable non-cultivable respiratory pathogens in 36% of nasal swabs. This may have implications for the pathogenesis of OM including persistence of infection despite aggressive therapies.

ConclusionNasal bacterial load was significantly higher among Aboriginal children and may explain their increased risk of suppurative OM. It was also positively correlated with ear state. We believe that a reduction in bacterial load in high-risk populations may be required before dramatic reductions in OM can be achieved.

Electronic supplementary materialThe online version of this article doi:10.1186-1472-6815-6-10 contains supplementary material, which is available to authorized users.

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Autor: Heidi Smith-Vaughan - Roy Byun - Mangala Nadkarni - Nicholas A Jacques - Neil Hunter - Stephen Halpin - Peter S Morris -


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