Etiology and management of infections in chronic obstructive pulmonary disease

Exacerbations of chronic obstructive pulmonary disease (COPD) due to pathogenic microorganisms are a major cause of morbidity and mortality. Three major classes of pathogenic microorganisms have been implicated in exacerbations of COPD: aerobic bacteria, viruses, and atypical bacteria. Sputum cultures and bronchoscopic protected-specimen brush cultures are positive for aerobic bacteria in half the exacerbations of COPD. Nontypeable Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis are the most frequently isolated bacterial pathogens. Viral infections are associated with one third of exacerbations. Chlamydia pneumoniae infection is associated with 5% to 10% of exacerbations whereas Mycoplasma infection has been seen only rarely in this setting. As many as half of bacterial exacerbations of COPD are now caused by pathogens that are resistant to aminopenicillins (e.g., amoxicillin). An approach to empiric antibiotic therapy of acute exacerbations on the basis of stratifying exacerbations and patients and choosing antibiotic therapy accordingly is outlined.