Bacterial infections in patients requiring admission for an acute exacerbation of COPD; a 1-year prospective study

STUDY OBJECTIVE: To investigate the frequency of respiratory bacterial infections in hospitalized patients, admitted with an acute exacerbation of chronic obstructive pulmonary disease (COPD), to identify the responsible pathogens by sputum culture and to assess patient characteristics in relation to sputum culture results. METHODS: We prospectively evaluated clinical data and sputum culture results of 171 patients, admitted to the pulmonology department of the University Hospital Maastricht with an acute exacerbation of COPD from 1st January 1999 until 31st December 1999. RESULTS: Eighty-five patients (50%) had positive sputum cultures, indicating the presence of bacterial infection. Pathogens most frequently isolated were: Haemophilus influenzae (45%), Streptococcus pneumoniae (27%), and Pseudomonas aeruginosa (15%). Patients with more severely compromised lung function had a higher incidence of bacterial infections (P = 0.026). There were no significant differences in age, lung function parameters, blood gas results and length of hospital stay between patients with and without bacterial infection. There were no correlations between the type of bacteria isolated and clinical characteristics. CONCLUSION: Incidence of bacterial infection during acute exacerbations of COPD is about 50%. Patients with and without bacterial infection are not different in clinical characteristics or in outcome parameters. Patients with lower FEV1 have a higher incidence of bacterial infections, but there is no difference in the type of bacterial infection. In the future, the pathogenic role of bacterial infection in exacerbations of COPD should be further investigated, especially the role of bacterial infection in relation to local and systemic inflammation.