title: Bacterial colonization increases daily symptoms in patients with chronic obstructive pulmonary disease.
abstract: BACKGROUND
  Respiratory pathogens are frequently isolated from the airways of patients with chronic obstructive pulmonary disease (COPD) in the absence of an exacerbation. This bacterial "colonization" by potential pathogens is associated with host inflammatory and immune responses, which could increase respiratory symptoms.
  
  
  OBJECTIVE
  To study whether bacterial colonization impacts daily respiratory symptoms in COPD.
  
  
  METHODS
  In a longitudinal prospective observational study of COPD, patients recorded daily symptoms electronically on the Breathlessness, Cough, and Sputum Scale (BCSS). Sputum cultures and quantitative polymerase chain reaction (PCR) were performed every 2 weeks. The relationship of BCSS and bacterial colonization was analyzed with generalized linear mixed effects models, after controlling for exacerbations, weather conditions, lung function, and demographic variables.
  
  
  RESULTS
  A total of 41 patients recorded daily symptoms for 12,527 days. The average BCSS score was higher during the periods of colonization, determined by sputum culture with one or more of the following pathogens: nontypeable Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pneumoniae, and Pseudomonas aeruginosa, compared to periods without colonization (5.28 vs. 4.46; P = 0.008) after controlling for confounding variables. The finding did not change when colonization was defined by quantitative PCR (average BCSS, 4.77 vs. 4.25; P = 0.006). Sputum IL-8 levels were elevated with bacterial colonization.
  
  
  CONCLUSIONS
  Even in the absence of clinical exacerbation, colonization by bacterial pathogens in COPD was associated with a clinically significant moderate increase in daily symptoms, likely mediated by increased airway inflammation. Novel therapies that decrease bacterial colonization in COPD could improve daily symptoms and quality of life.
authors.affiliation: 1 Chesapeake Pulmonary and Critical Care Medicine, Chesapeake, Virginia.
authors.forename: Himanshu
authors.initials: H
authors.lastname: Desai
authors.forename: Karen
authors.initials: K
authors.lastname: Eschberger
authors.forename: Catherine
authors.initials: C
authors.lastname: Wrona
authors.forename: Lori
authors.initials: L
authors.lastname: Grove
authors.forename: Aarti
authors.initials: A
authors.lastname: Agrawal
authors.forename: Brydon
authors.initials: B
authors.lastname: Grant
authors.forename: Jingjing
authors.initials: J
authors.lastname: Yin
authors.forename: G Iyer
authors.initials: GI
authors.lastname: Parameswaran
authors.forename: Timothy
authors.initials: T
authors.lastname: Murphy
authors.forename: Sanjay
authors.initials: S
authors.lastname: Sethi
mesh_terms: D000368:Aged; D003371:Cough / Q000209:etiology*; D004417:Dyspnea / Q000209:etiology*; D005260:Female; D006193:Haemophilus influenzae / Q000302:isolation & purification; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D001936:Moraxella catarrhalis / Q000302:isolation & purification; D011446:Prospective Studies; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000378:metabolism / Q000382:microbiology*; D013183:Sputum / Q000378:metabolism / Q000382:microbiology*; D013296:Streptococcus pneumoniae / Q000302:isolation & purification
chemical_list: D016209:Interleukin-8