Longitudinal nasopharyngeal carriage and antibiotic resistance of respiratory bacteria in indigenous Australian and Alaska native children with bronchiectasis

Hare, Kim M., Singleton, Rosalyn J., Grimwood, Keith, Valery, Patricia C., Cheng, Allen C., Morris, Peter S., Leach, Amanda J., Smith-Vaughan, Heidi C., Chatfield, Mark, Redding, Greg, Reasonover, Alisa L., McCallum, Gabrielle B., Chikoyak, Lori, McDonald, Malcolm, Brown, Ngiare, Torzillo, Paul J., and Chang, Anne B. (2013) Longitudinal nasopharyngeal carriage and antibiotic resistance of respiratory bacteria in indigenous Australian and Alaska native children with bronchiectasis. PLoS ONE, 8 (8). e70478. pp. 1-9.

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Abstract

Background: Indigenous children in Australia and Alaska have very high rates of chronic suppurative lung disease (CSLD)/bronchiectasis. Antibiotics, including frequent or long-term azithromycin in Australia and short-term beta-lactam therapy in both countries, are often prescribed to treat these patients. In the Bronchiectasis Observational Study we examined over several years the nasopharyngeal carriage and antibiotic resistance of respiratory bacteria in these two PCV7-vaccinated populations.

Methods: Indigenous children aged 0.5–8.9 years with CSLD/bronchiectasis from remote Australia (n = 79) and Alaska (n = 41) were enrolled in a prospective cohort study during 2004–8. At scheduled study visits until 2010 antibiotic use in the preceding 2-weeks was recorded and nasopharyngeal swabs collected for culture and antimicrobial susceptibility testing. Analysis of respiratory bacterial carriage and antibiotic resistance was by baseline and final swabs, and total swabs by year.

Results: Streptococcus pneumoniae carriage changed little over time. In contrast, carriage of Haemophilus influenzae declined and Staphylococcus aureus increased (from 0% in 2005–6 to 23% in 2010 in Alaskan children); these changes were associated with increasing age. Moraxella catarrhalis carriage declined significantly in Australian, but not Alaskan, children (from 64% in 2004–6 to 11% in 2010). While beta-lactam antibiotic use was similar in the two cohorts, Australian children received more azithromycin. Macrolide resistance was significantly higher in Australian compared to Alaskan children, while H. influenzae beta-lactam resistance was higher in Alaskan children. Azithromycin use coincided significantly with reduced carriage of S. pneumoniae, H. influenzae and M. catarrhalis, but increased carriage of S. aureus and macrolide-resistant strains of S. pneumoniae and S. aureus (proportion of carriers and all swabs), in a 'cumulative dose-response' relationship.

Conclusions: Over time, similar (possibly age-related) changes in nasopharyngeal bacterial carriage were observed in Australian and Alaskan children with CSLD/bronchiectasis. However, there were also significant frequency-dependent differences in carriage and antibiotic resistance that coincided with azithromycin use.

Item ID: 28920
Item Type: Article (Research - C1)
ISSN: 1932-6203
Additional Information:

This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.

Funders: National Health and Medical Research Council (NHMRC), Centre for Research Excellence in Lung Health of Aboriginal and Torres Strait Islanders, National Institute of Health (NIH), USA
Projects and Grants: 389837, 545223, 1040830
Date Deposited: 26 Aug 2013 04:46
FoR Codes: 11 MEDICAL AND HEALTH SCIENCES > 1102 Cardiovascular Medicine and Haematology > 110203 Respiratory Diseases @ 100%
SEO Codes: 92 HEALTH > 9203 Indigenous Health > 920302 Aboriginal and Torres Strait Islander Health - Health Status and Outcomes @ 100%
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