Infectious etiologies in acute exacerbation of COPD

Acute exacerbation (AE) is a frequent episode during the prolonged chronic course of chronic obstructive pulmonary disease (COPD), which entails signi ficant morbidity and mortality. The purpose of this study was to determine the frequency distribution of infectious etiologies in these episodes. Two hundred forty hospitalizations for AECOPD were included in a prospective, p urely serologically based study. Paired sera were obtained for each of the hospitalizations and were tested using immunofluorescence or EIA methods to identify 13 different pathogens. Only significant changes in antibody tite rs were considered diagnostic. The mean age ( +/- SD) of the patients was 6 6.8 +/- 9.0 years and 179 (84%) were males. In 175 (72.9%) hospitalizations at least one infectious etiology was identified. In 117 (48.8%) hospitaliz ations at least one of 7 viral etiologies was identified. In 72 (30.0%) hos pitalizations at least one of the following atypical bacteria was identifie d: Legionella spp. in 40 (16.7%), Mycoplasma pneumoniae in 34 (14.2%), and Coxiella burnetii in a single hospitalization. In 58 (24.2%) hospitalizatio ns at least one classic bacterial etiology was found: Streptococcus pneumon iae in 48 (20.0%), Hemophilus influenzae in 10 (4.2%) and Moraxella catarrh alis in 9 (3.8%). More than one etiology was found in 72 (30.0%) hospitaliz ations. There were no significant differences in the etiologic distribution when the patients were classified by severity of airway obstruction or the clinical type of the exacerbation. We conclude that in most cases of hospi talization due to AECOPD the infectious etiology is viral or atypical bacte ria and is classic bacteria in only a minority of cases. More than one etio logic cause can be identified in a third of the cases. The frequency distri bution of the etiologies is not associated with the severity of airway obst ruction or the clinical type of the exacerbation. The results of our study suggest that atypical bacteria should be covered in antibiotic regimens rec ommended for AECOPD. This issue should be addressed in future studies. (C) 2001 Elsevier Science Inc. All rights reserved.