Bacteriological differences between COPD exacerbation and community-acquired pneumonia.

Objective: To study the differences in pathogen distribution and antibiotic susceptibility between patients with COPD exacerbation and patients with community-acquired pneumonia, and develop guidance for antibiotic treatment of those conditions.

Methods: We retrospectively analyzed the medical records of 586 COPD-exacerbation patients and 345 community-acquired-pneumonia patients from January 2007 to December 2008, including sputum culture results, antibiotic susceptibilities of the microorganisms, and clinical characteristics.

Results: 276 (47%) of the COPD-exacerbation patients, and 183 (53%) of the community-acquired-pneumonia patients had a positive sputum culture. In order, the most common pathogens in the COPD-exacerbation patients were Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Acinetobacter baumannii, and Haemophilus influenzae. The most common pathogens in the community-acquired-pneumonia patients were Streptococcus pneumoniae, H. influenzae, K. pneumoniae, S. aureus, and E. coli.

Conclusions: P. aeruginosa was the most common pathogen in our patients with COPD exacerbation, and S. pneumoniae was the most common in our patients with community-acquired pneumonia. P. aeruginosa is especially common in the patients with serious or extremely serious COPD.