Journal Article

Airway Bacterial Concentrations and Exacerbations of Chronic Obstructive Pulmonary Disease

Eschberger, Karen, Lobbins, Phyllis, Sethi, Sanjay, Grant, Brydon J. B, Murphy, Timothy F, Sethi, Rohin, Cai, Xueya

2007

Overview

Increased bacterial concentration (load) in the lower airways and new bacterial strain acquisition have been posited as mechanisms for chronic obstructive pulmonary disease (COPD) exacerbations. Bacterial concentrations are higher during exacerbation than during stable disease; however, these studies are cross sectional and devoid of strain typing. To determine if the increased bacterial concentrations function as a separate mechanism for exacerbation induction independent of new strain acquisition. In a prospective, longitudinal cohort of patients with COPD, the relationship between exacerbation occurrence, sputum bacterial concentrations, and new strain acquisition was examined. Clinical information, quantitative sputum cultures, and molecular typing of potential bacterial pathogen isolates. Over 81 months, 104 subjects completed 3,009 clinic visits, 560 (19.6%) during exacerbations and 2,449 (80.4%) during stable disease. Among preexisting strains, sputum concentrations of Nontypeable Haemophilus influenzae and Haemophilus haemolyticus were not different in exacerbation versus stable disease. Moraxella catarrhalis (stable, 10(8.38 +/- 0.13) [mean +/- SEM] vs. exacerbation, 10(7.78 +/- 0.26); p = 0.02) and Streptococcus pneumoniae (stable, 10(8.42 +/- 0.21) vs. exacerbation, 10(7.76 +/- 0.52); p = 0.07) concentrations were lower during exacerbations compared with stable periods. Concentrations of new strains of H. influenzae (stable, 10(7.28 +/- 0.15) vs. exacerbation, 10(7.76 +/- 0.17); p = 0.04) and M. catarrhalis (stable, 10(7.85 +/- 0.15) vs. exacerbation, 10(8.37 +/- 0.14); p = 0.02), were increased during exacerbations; however, the differences were small. Change in bacterial load is unlikely to be an important mechanism for exacerbations. Better understanding of the host-pathogen interaction, rather than enumerating bacteria in respiratory samples, is required to provide new insights into bacterial infection in COPD.

• Publisher: Am Thoracic Soc,American Lung Association,Oxford University Press
• Subject: Aged / Aged, 80 and over / Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy / Bacteria / Bacterial infections / Biological and medical sciences / Chronic obstructive pulmonary disease / Chronic obstructive pulmonary disease, asthma / Colony Count, Microbial / Female / Haemophilus - isolation & purification / Haemophilus influenzae / Humans / Intensive care medicine / Longitudinal Studies / Male / Medical sciences / Middle Aged / Moraxella (Branhamella) catarrhalis - isolation & purification / Moraxella catarrhalis / Pathogens / Pneumology / Prospective Studies / Pulmonary Disease, Chronic Obstructive - physiopathology / Pulmonary hypertension. Acute cor pulmonale. Pulmonary embolism. Pulmonary vascular diseases / Sputum - microbiology / Streptococcus infections / Streptococcus pneumoniae / Streptococcus pneumoniae - isolation & purification