Relationship between microbiota diversity and age in cystic fibrosis patients

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Cystic fibrosis Cystic fibrosis (CF), a hereditary chronic disease affecting pulmonary and digestive function in over 70,000 individuals worldwide, has proven difficult to analyze in terms of the relationships among lung function, patient age, and microbial colonization of the airways. In the first study of airway microbial colonies in CF patients ranging from neonates (9 months) to adults (72 years), younger patients have been recorded as having more diverse airway bacteria than their older counterparts. This could imply that more limited bacterial diversity and deteriorating airway health correlate.

The study, conducted at the University of California in San Francisco, analyzed deep-throat swab and expectorated sputum samples from 51 patients at the University’s pediatric and adult CF clinics. Analysis was performed using the PhyloChip microarray, which enabled control for variations in fragmentation, biotinylation, hybridization, washing, staining, and scanning; the resulting data were used to generate a phylogenetic distance matrix. Despite these and many other precautions taken, the study suggests that factors such as unmeasured antibiotic use, chest physical therapy, adherence, nutrition, and other potential variables might encourage more stringent inquiry into the subject of airway microbial diversity as a function of patient age. With the affirmation that bacterial community structure and composition are substantial factors in defining the functionality of microbial assemblage and host health status, future research has the potential to further explain pulmonary health in terms of airway microbiota diversity.

Airway Microbiota and Pathogen Abundance in Age-Stratified Cystic Fibrosis Patients. 2010 PLoS ONE 5(6): e11044. doi:10.1371/journal.pone.0011044
Bacterial communities in the airways of cystic fibrosis (CF) patients are, as in other ecological niches, influenced by autogenic and allogenic factors. However, our understanding of microbial colonization in younger versus older CF airways and the association with pulmonary function is rudimentary at best. Using a phylogenetic microarray, we examine the airway microbiota in age stratified CF patients ranging from neonates (9 months) to adults (72 years). From a cohort of clinically stable patients, we demonstrate that older CF patients who exhibit poorer pulmonary function possess more uneven, phylogenetically-clustered airway communities, compared to younger patients. Using longitudinal samples collected form a subset of these patients a pattern of initial bacterial community diversification was observed in younger patients compared with a progressive loss of diversity over time in older patients. We describe in detail the distinct bacterial community profiles associated with young and old CF patients with a particular focus on the differences between respective “early” and “late” colonizing organisms. Finally we assess the influence of Cystic Fibrosis Transmembrane Regulator (CFTR) mutation on bacterial abundance and identify genotype-specific communities involving members of the Pseudomonadaceae, Xanthomonadaceae, Moraxellaceae and Enterobacteriaceae amongst others. Data presented here provides insights into the CF airway microbiota, including initial diversification events in younger patients and establishment of specialized communities of pathogens associated with poor pulmonary function in older patient populations.


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