Influence of biofim on the bronchial microbiome in COPD patients colonized or infected bypseudomonas aeruginosa

The recovery of Pseudomonas aeruginosa from respiratory samples of COPD patients has been associated with impaired lung function and recurrent exacerbations, partly due to strain-dependent factors such as biofilm formation. Aims: To analyse the bronchial microbiome of COPD patients with positive cultures for P.aeruginosa associated with either colonization or infection, and differentiated according to biofilm production, both in stability and exacerbation. Methods: Sputum samples with positive cultures for P.aeruginosa were obtained from 21 COPD patients during stability (n=18) and exacerbation (n=23), and analysed by 16S rRNA gene amplification and pyrosequencing. Biofilm-forming capacity of P. aeruginosa was examined using crystal violet in a static microtiter plate assay. Sputum samples were classified according to the biofilm-forming capacity of P.aeruginosa (low/high), assessing the differences between both groups, both in stability and exacerbation.RESULTS:No significant differences in biodiversity parameters (Shannon and Chao1) were found between low and high biofilm-forming groups. However, the bronchial microbiome of the high biofilm-forming group showed higher relative abundance of bacterial Operational Taxonomic Units (12 and 9 OTUs during stability and exacerbation, respectively), and represented up to 10% of the relative abundance in the sample. Conclusions: In COPD patients colonized or infected by P. aeruginosa , biofilm production was associated with an overgrowth of some bacterial OTUs, which attained a relative abundance of up to 10%. Accordingly, a biofilm environment undermined a change in the bronchial microbiome identifiable through 16srRNA analyses.