BackgroundBronchiectasis is accompanied by chronic bronchial infection that may drive disease progression. However, the evidence base for antibiotic therapy is limited. DNA based methods offer better identification and quantification of microbial constituents of sputum than standard clinical culture and may help inform patient management strategies. Our study objective was to determine the longitudinal variability of the non-cystic fibrosis (CF) bronchiectasis microbiome in sputum with respect to clinical variables. Eighty-five patients with non-CF bronchiectasis and daily sputum production were recruited from outpatient clinics and followed for six months. Monthly sputum samples and clinical measurements were taken, together with additional samples during exacerbations. 16S rRNA gene sequencing of the sputum microbiota was successful for 381 samples from 76 patients and analysed in conjunction with clinical data.ResultsMicrobial communities were highly individual in composition and stability, usually with limited diversity and often containing multiple pathogens. When compared to DNA sequencing, microbial culture had restricted sensitivity in identifying common pathogens such as Pseudomonas aeruginosa, Haemophilus influenzae, Moraxella catarrhalis. With some exceptions, community characteristics showed poor correlations with clinical features including underlying disease, antibiotic use and exacerbations, with the subject showing the strongest association with community structure. When present, the pathogens mucoid Pseudomonas aeruginosa and Haemophilus influenzae may also shape the structure of the rest of the microbial community.ConclusionsThe use of microbial community analysis of sputum added to information from microbial culture. A simple model of exacerbations driven by bacterial overgrowth was not supported, suggesting a need for revision of principles for antibiotic therapy. In individual patients, the management of chronic bronchial infection may be improved by therapy specific to their microbiome, taking into account pathogen load, community stability, and acute and chronic community responses to antibiotics.

2Bronchiectasis is accompanied by chronic bronchial infection that may drive disease progression.3 However, the evidence base for antibiotic therapy is limited. DNA based methods offer better 4 identification and quantification of microbial constituents of sputum than standard clinical culture and 5 may help inform patient management strategies. Our study objective was to determine the longitudinal 6 variability of the non-CF bronchiectasis microbiome in sputum with respect to clinical variables. 7 Eighty-five patients with non-cystic fibrosis (CF) bronchiectasis and daily sputum production were 8 recruited from outpatient clinics and followed for six months. Monthly sputum samples and clinical 9 measurements were taken, together with additional samples during exacerbations. 16S rRNA gene 1 0 sequencing of the sputum microbiota was successful for 381 samples from 76 patients and analysed 1 1 in conjunction with clinical data.

Poster sessionsThorax 2012;67(Suppl 2):A1-A204 A139importantly a significant number of first PA isolations over a short follow-up period. Furthermore, a large percentage of patients had no microbe isolated (including at exacerbation) suggesting a possible use of future molecular microbe techniques. . Radiographic evidence of 'damaged and dilated bronchi' can be seen on CT Thorax in up to 50% of COPD patients. However the contribution of radiographic bronchiectasis to the clinical course of COPD is not fully understood. We aimed to determine the impact of bronchiectasis on lung function, sputum microbiology and outcomes in COPD patients, independent of coexisting emphysema and bronchial wall thickening (BWT). COPD-RELATED BRONCHIECTASISMethods COPD patients admitted with first exacerbation 1998-2008 were identified retrospectively using ICD10 codes J44.0,1,8,9. Patients with high resolution CT images within 2 years of admission were included. CT scans were graded by consensus of 2 senior thoracic radiologists for severity of bronchiectasis, emphysema and BWT on a 5 point scale (0-absent, 1-minor, 2-mild, 3-moderate, 4-severe). Operational definitions were set prior to scan review and radiologists were blinded to clinical parameters. Results 406 patients (71±11years, 56% male, FEV 1 52±23% predicted) were included. 278 (69%) patients had bronchiectasis: minor, 112 (40%); mild, 81 (29%); moderate, 62 (22%); severe 23 (8%). There was considerable overlap between bronchiectasis and other pathologies (figure). Bronchiectasis severity correlated with severity of BWT (r=0.276, p<0.001) and emphysema (r=0.120, p=0.015). After adjustment for severity of emphysema and BWT, increasing severity bronchiectasis was not an independent predictor of lung function parameters, but independently determined isolation of Pseudomonas aeruginosa (Odds ratio (OR) 1.39 (95% CI 1.07-1.80), p=0.013) and atypical mycobacteria from sputum cultures (OR 2.44 (95% CI 1.04-5.69), p=0.040). After correction for increasing severity emphysema, BWT, age, gender and comorbidities, increasing severity bronchiectasis determined annual admissions (regression coefficient B=0.14 (95% CI 0.00-0.28), p=0.044) and inpatient days (B=2.1 (95% CI 0.8-3.4), p=0.001) for respiratory causes, but did not influence survival from first hospital admission (p=0.257). Conclusions Radiographic bronchiectasis in COPD patients is associated with increased respiratory infection and hospitalisation, independent of coexisting emphysema and BWT. COPD-related bronchiectasis is therefore a diagnosis with important clinical implications. Further research should determine whether treatment strategies for non-CF bronchiectasis can improve the clinical course of COPD-related bronchiectasis.

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