Infectious etiology of acute exacerbations in severe COPD patients

Abstract

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.

Keywords: Acute exacerbation; Chronic obstructive pulmonary disease; Haemophilus influenzae; Pseudomonas aeruginosa; Streptococcus pneumoniae.