Lung microbiota and bacterial abundance in patients with bronchiectasis when clinically stable and during exacerbation.
BACKGROUND
Characterization of bacterial populations in infectious respiratory diseases will provide improved understanding of the relationship between the lung microbiota, disease pathogenesis, and treatment outcomes.


OBJECTIVE
To comprehensively define lung microbiota composition during stable disease and exacerbation in patients with bronchiectasis.


METHODS
Sputum was collected from patients when clinically stable and before and after completion of antibiotic treatment of exacerbations. Bacterial abundance and community composition were analyzed using anaerobic culture and 16S rDNA pyrosequencing.


RESULTS
In clinically stable patients, aerobic and anaerobic bacteria were detected in 40 of 40 (100%) and 33 of 40 (83%) sputum samples, respectively. The dominant organisms cultured were Pseudomonas aeruginosa (n = 10 patients), Haemophilus influenzae (n = 12), Prevotella (n = 18), and Veillonella (n = 13). Pyrosequencing generated more than 150,000 sequences, representing 113 distinct microbial taxa; the majority of observed community richness resulted from taxa present in low abundance with similar patterns of phyla distribution in clinically stable patients and patients at the onset of exacerbation. After treatment of exacerbation, there was no change in total (P = 0.925), aerobic (P = 0.917), or anaerobic (P = 0.683) load and only a limited shift in community composition. Agreement for detection of bacteria by culture and pyrosequencing was good for aerobic bacteria such as P. aeruginosa (κ = 0.84) but poorer for other genera including anaerobes. Lack of agreement was largely due to bacteria being detected by pyrosequencing but not by culture.


CONCLUSIONS
A complex microbiota is present in the lungs of patients with bronchiectasis and remains stable through treatment of exacerbations, suggesting that changes in microbiota composition do not account for exacerbations.
Cystic Fibrosis and Airways Microbiology Research Group, School of Medicine, Dentistry, and Biomedical Sciences, Queen's University Belfast, Belfast, United Kingdom. m.tunney@qub.ac.uk
Michael M
MM
Tunney
Gisli G
GG
Einarsson
Lan
L
Wei
Maire
M
Drain
Erich R
ER
Klem
Chris
C
Cardwell
Madeleine
M
Ennis
Richard C
RC
Boucher
Matthew C
MC
Wolfgang
J Stuart
JS
Elborn
D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001987:Bronchiectasis / Q000188:drug therapy* / Q000382:microbiology*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008168:Lung / Q000382:microbiology*; D008297:Male; D054892:Metagenome; D013183:Sputum / Q000382:microbiology
D000900:Anti-Bacterial Agents