title: Colour of sputum is a marker for bacterial colonisation in chronic obstructive pulmonary disease.
abstract: BACKGROUND
  Bacterial colonisation in chronic obstructive pulmonary disease (COPD) contributes to airway inflammation and modulates exacerbations. We assessed risk factors for bacterial colonisation in COPD.
  
  
  METHODS
  Patients with stable COPD consecutively recruited over 1 year gave consent to provide a sputum sample for microbiologic analysis. Bronchial colonisation by potentially pathogenic microorganisms (PPMs) was defined as the isolation of PPMs at concentrations of > or =102 colony-forming units (CFU)/mL on quantitative bacterial culture. Colonised patients were divided into high (>105 CFU/mL) or low (<105 CFU/mL) bacterial load.
  
  
  RESULTS
  A total of 119 patients (92.5% men, mean age 68 years, mean forced expiratory volume in one second [FEV1] [% predicted] 46.4%) were evaluated. Bacterial colonisation was demonstrated in 58 (48.7%) patients. Patients with and without bacterial colonisation showed significant differences in smoking history, cough, dyspnoea, COPD exacerbations and hospitalisations in the previous year, and sputum colour. Thirty-six patients (62% of those colonised) had a high bacterial load. More than 80% of the sputum samples with a dark yellow or greenish colour yielded PPMs in culture. In contrast, only 5.9% of white and 44.7% of light yellow sputum samples were positive (P < 0.001). Multivariate analysis showed an increased degree of dyspnoea (odds ratio [OR] = 2.63, 95% confidence interval [CI] 1.53-5.09, P = 0.004) and a darker sputum colour (OR = 4.11, 95% CI 2.30-7.29, P < 0.001) as factors associated with the presence of PPMs in sputum.
  
  
  CONCLUSIONS
  Almost half of our population of ambulatory moderate to very severe COPD patients were colonised with PPMs. Patients colonised present more severe dyspnoea, and a darker colour of sputum allows identification of individuals more likely to be colonised.
authors.affiliation: Fundació Clínic, Institut D'Investigacions Biomèdiques August Pi i Sunyer, Ciber de Enfermedades Respiratorias, Barcelona, Spain. marcm@separ.es
authors.forename: Marc
authors.initials: M
authors.lastname: Miravitlles
authors.forename: Alicia
authors.initials: A
authors.lastname: Marín
authors.forename: Eduard
authors.initials: E
authors.lastname: Monsó
authors.forename: Sara
authors.initials: S
authors.lastname: Vilà
authors.forename: Cristian
authors.initials: C
authors.lastname: de la Roza
authors.forename: Ramona
authors.initials: R
authors.lastname: Hervás
authors.forename: Cristina
authors.initials: C
authors.lastname: Esquinas
authors.forename: Marian
authors.initials: M
authors.lastname: García
authors.forename: Laura
authors.initials: L
authors.lastname: Millares
authors.forename: Josep
authors.initials: J
authors.lastname: Morera
authors.forename: Antoni
authors.initials: A
authors.lastname: Torres
mesh_terms: D000368:Aged; D000553:Ambulatory Care; D001980:Bronchi / Q000382:microbiology* / Q000503:physiopathology; D015169:Colony Count, Microbial; D003116:Color; D003430:Cross-Sectional Studies; D004417:Dyspnea / Q000382:microbiology; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011237:Predictive Value of Tests; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000382:microbiology* / Q000503:physiopathology; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D013030:Spain; D013183:Sputum / Q000382:microbiology*; D014797:Vital Capacity
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