Relative frequency of bacterial pathogens isolated from 14 antibiotic comparison trials in exacerbations of chronic obstructive pulmonary disease*
Relative frequency of bacterial pathogens isolated from 14 antibiotic comparison trials in exacerbations of chronic obstructive pulmonary disease*
Pathogen
Percentage of bacterial isolates (range)
Haemophilus influenzae
13 to 50
Moraxella catarrhalis
9 to 21
Streptococcus pneumoniae
7 to 26
Pseudomonas aeruginosa
1 to 13
* Enterobacteriaceae have been isolated from the respiratory tract of 3 to 19 percent of patients with chronic obstructive pulmonary disease (COPD) exacerbations and Staphylococcus aureus has been isolated from the respiratory tract of 1 to 20 percent of patients with COPD exacerbations, but their pathogenic significance in this setting has not been defined. Haemophilus parainfluenzae has been isolated from the respiratory tract of 2 to 32 percent of patients with COPD exacerbations, but these organisms are unlikely to cause COPD exacerbations.