Infectious etiology of acute exacerbations in severe COPD patients

Objectives: Since the new GOLD guidelines were implemented no data have been published about the etiology of acute exacerbations (AECOPD) in severe COPD patients with a different frequency of annual episodes. Methods: One hundred and eleven COPD patients (FEV1 < 50%) were prospectively followed up for a year. Good-quality sputum samples recovered during AECOPD were processed, including quantitative culture and PCR detection of atypical bacteria. Results: A total of 188 sputum samples were obtained from AECOPD episodes. Forty patients had a single episode, and 71 patients had >= 2. In 128 episodes a single pathogen was isolated, while 42 episodes were polymicrobial (>= 2 pathogens). Overall, the most frequent pathogen isolated was Pseudomonas aeruginosa (n = 54), followed by Haemophilus influenzae (n = 37), Streptococcus pneumoniae (n = 31), Moraxella catarrhalis (n = 29) and Staphylococcus aureus (n = 12). P. aeruginosa was the most frequent in both groups of patients (35% and 27% in those with 1 and >= 2 AECOPD, respectively). H. influenzae was associated with patients with a single annual AECOPD (33% vs. 16%; P = 0.006), while Enterobacteriaceae were associated with frequent exacerbators (0% vs. 12%; P < 0.044). Conclusion: Overall, P. aeruginosa was the most frequent pathogen isolated from exacerbations. However, different bacterial etiology was observed depending on the number of annual episodes. (C) 2013 The British Infection Association. Published by Elsevier Ltd. All rights reserved.