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ISME J. 2015 Jan;9(1):217-25. doi: 10.1038/ismej.2014.124. Epub 2014 Jul 18.

Predominant pathogen competition and core microbiota divergence in chronic airway infection.

Author information

1
1] SAHMRI Infection and Immunity Theme, School of Medicine, Flinders University, Adelaide, South Australia, Australia [2] Immunity, Infection, and Inflammation Program, Mater Research Institute, University of Queensland, Translational Research Institute, Woolloongabba, Queensland, Australia.
2
NERC Centre for Ecology and Hydrology, Wallingford, UK.
3
1] Immunity, Infection, and Inflammation Program, Mater Research Institute, University of Queensland, Translational Research Institute, Woolloongabba, Queensland, Australia [2] Department of Respiratory Medicine, Mater Adult Hospital, South Brisbane, Queensland, Australia.

Abstract

Chronic bacterial lung infections associated with non-cystic fibrosis bronchiectasis represent a substantial and growing health-care burden. Where Pseudomonas aeruginosa is the numerically dominant species within these infections, prognosis is significantly worse. However, in many individuals, Haemophilus influenzae predominates, a scenario associated with less severe disease. The mechanisms that determine which pathogen is most abundant are not known. We hypothesised that the distribution of H. influenzae and P. aeruginosa would be consistent with strong interspecific competition effects. Further, we hypothesised that where P. aeruginosa is predominant, it is associated with a distinct 'accessory microbiota' that reflects a significant interaction between this pathogen and the wider bacterial community. To test these hypotheses, we analysed 16S rRNA gene pyrosequencing data generated previously from 60 adult bronchiectasis patients, whose airway microbiota was dominated by either P. aeruginosa or H. influenzae. The relative abundances of the two dominant species in their respective groups were not significantly different, and when present in the opposite pathogen group the two species were found to be in very low abundance, if at all. These findings are consistent with strong competition effects, moving towards competitive exclusion. Ordination analysis indicated that the distribution of the core microbiota associated with each pathogen, readjusted after removal of the dominant species, was significantly divergent (analysis of similarity (ANOSIM), R=0.07, P=0.019). Taken together, these findings suggest that both interspecific competition and also direct and/or indirect interactions between the predominant species and the wider bacterial community may contribute to the predominance of P. aeruginosa in a subset of bronchiectasis lung infections.

PMID:
25036925
PMCID:
PMC4274430
DOI:
10.1038/ismej.2014.124
[Indexed for MEDLINE]
Free PMC Article

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