RATIONALE: 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. OBJECTIVES: To determine if the increased bacterial concentrations function as a separate mechanism for exacerbation induction independent of new strain acquisition. METHODS: In a prospective, longitudinal cohort of patients with COPD, the relationship between exacerbation occurrence, sputum bacterial concentrations, and new strain acquisition was examined. MEASUREMENTS AND MAIN RESULTS: 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. CONCLUSIONS: 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.
RATIONALE: 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. OBJECTIVES: To determine if the increased bacterial concentrations function as a separate mechanism for exacerbation induction independent of new strain acquisition. METHODS: In a prospective, longitudinal cohort of patients with COPD, the relationship between exacerbation occurrence, sputum bacterial concentrations, and new strain acquisition was examined. MEASUREMENTS AND MAIN RESULTS: 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. CONCLUSIONS: 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.
Authors: M Woodhead; F Blasi; S Ewig; J Garau; G Huchon; M Ieven; A Ortqvist; T Schaberg; A Torres; G van der Heijden; R Read; T J M Verheij Journal: Clin Microbiol Infect Date: 2011-11 Impact factor: 8.067
Authors: Christopher J Harvey; Rajesh K Thimmulappa; Sanjay Sethi; Xiaoni Kong; Lonny Yarmus; Robert H Brown; David Feller-Kopman; Robert Wise; Shyam Biswal Journal: Sci Transl Med Date: 2011-04-13 Impact factor: 17.956
Authors: Marc Miravitlles; Alicia Marín; Eduard Monsó; Sara Vilà; Cristian de la Roza; Ramona Hervás; Cristina Esquinas; Marian García; Laura Millares; Josep Morera; Antoni Torres Journal: Respir Res Date: 2010-05-14
Authors: Daniel Drömann; Jan Rupp; Kristina Rohmann; Sinia Osbahr; Artur J Ulmer; Sebastian Marwitz; Kristina Röschmann; Mahdi Abdullah; Holger Schultz; Ekkehard Vollmer; Peter Zabel; Klaus Dalhoff; Torsten Goldmann Journal: Respir Res Date: 2010-05-31