Microbiologic determinants of exacerbation in chronic obstructive pulmonary disease

Antoni Rosell, Eduard Monsó*, Néstor Soler, Ferràn Torres, Joaquim Angrill, Gerdt Riise, Rafael Zalacaín, Josep Morera, Antoni Torres

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

243 Citations (Scopus)


Background: The culture of bronchial secretions from the lower airway has been reported to be positive for potentially pathogenic microorganisms (PPMs) in patients with stable chronic obstructive pulmonary disease (COPD), but the determinants and effects of this bacterial load in the airway are not established. Methods: To determine the bronchial microbial pattern in COPD and its relationship with exacerbation, we pooled analysis of crude data from studies that used protected specimen brush sampling, with age, sex, smoking, lung function, and microbiologic features of the lower airway as independent variables and exacerbation as the outcome, using logistic regression modeling. Results: Of 337 study participants, 70 were healthy, 181 had stable COPD, and 86 had exacerbated COPD. Differences in the microbial characteristics in the participating laboratories were not statistically significant. A cut-off point of 102 colony-forming units (CFU) per milliliter or greater for the identification of abnormal positive culture results for PPMs was defined using the 95th percentile in the pooled analysis of healthy individuals. Bronchial colonization of 102 CFU/mL or greater by PPMs was found in 53 patients with stable COPD (29%) and in 46 patients with exacerbated COPD (54%) (P<.001, χ2 test), with a predominance of Haemophilus influenzae and Pseudomonas aeruginosa. Higher microbial loads were associated with exacerbation and showed a statistically significant dose-response relationship after adjustment for covariates (odds ratio, 3.62; 95% confidence interval, 1.47-8.90), but P aeruginosa persisted as a statistically significant risk factor after adjustment for microbial load (odds ratio, 11.12; 95% confidence interval, 1.17-105.82). Conclusions: One quarter of the patients with COPD are colonized by PPMs during their stable periods. Exacerbation is associated with the overgrowth of PPMs and with the appearance of P aeruginosa in the lower airway, which is associated with exacerbation symptoms independent of load.

Original languageAmerican English
Pages (from-to)891-897
Number of pages7
JournalArchives of Internal Medicine
Issue number8
Publication statusPublished - 25 Apr 2005


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