title: Pseudomonas aeruginosa isolates in severe chronic obstructive pulmonary disease: characterization and risk factors.
abstract: BACKGROUND
  Patients with severe chronic obstructive pulmonary disease (COPD) are at increased risk of infection by P. aeruginosa. The specific role of bronchiectasis in both infection and chronic colonization by this microorganism in COPD, however, remains ill defined.To evaluate the prevalence and risk factors for P. aeruginosa recovery from sputum in outpatients with severe COPD, characterizing P. aeruginosa isolates by pulsed-field gel electrophoresis (PFGE) and focusing on the influence of bronchiectasis on chronic colonization in these patients.
  
  
  METHODS
  A case-cohort study of 118 patients with severe COPD attended at a Respiratory Day Unit for an acute infectious exacerbation and followed up over one year. High-resolution CT scans were performed during stability for bronchiectasis assessment and sputum cultures were obtained during exacerbation and stability in all patients. P. aeruginosa isolates were genotyped by PFGE. Determinants of the recovery of P. aeruginosa in sputum and chronic colonization by this microorganism were assessed by multivariate analysis.
  
  
  RESULTS
  P. aeruginosa was isolated from 41 of the 118 patients studied (34.7%). Five of these 41 patients (12.2%) with P. aeruginosa recovery fulfilled criteria for chronic colonization. In the multivariate analysis, the extent of bronchiectasis (OR 9.8, 95% CI: 1.7 to 54.8) and the number of antibiotic courses (OR 1.7, 95% CI: 1.1 to 2.5) were independently associated with an increased risk of P. aeruginosa isolation. Chronic colonization was unrelated to the presence of bronchiectasis (p=0.75). In patients with chronic colonization the isolates of P. aeruginosa retrieved corresponded to the same clones during the follow-up, and most of the multidrug resistant isolates (19/21) were harbored by these patients.
  
  
  CONCLUSIONS
  The main risk factors for P. aeruginosa isolation in severe COPD were the extent of bronchiectasis and exposure to antibiotics. Over 10% of these patients fulfilled criteria for chronic colonization by P. aeruginosa and showed clonal persistence, independently of the presence of bronchiectasis.
authors: Department of Respiratory Medicine, Hospital de Sabadell, Institut Universitari Parc Taulí-UAB, Sabadell, Spain. mgallego@tauli.cat.
authors: Miguel
authors: M
authors: Gallego
authors: Xavier
authors: X
authors: Pomares
authors: Mateu
authors: M
authors: Espasa
authors: Eva
authors: E
authors: Castañer
authors: Mar
authors: M
authors: Solé
authors: David
authors: D
authors: Suárez
authors: Eduard
authors: E
authors: Monsó
authors: Concepción
authors: C
authors: Montón
mesh_terms: D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001987:Bronchiectasis / Q000150:complications* / Q000000981:diagnostic imaging; D016022:Case-Control Studies; D002908:Chronic Disease; D005260:Female; D005500:Follow-Up Studies; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011552:Pseudomonas Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000209:etiology; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000302:isolation & purification*; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000382:microbiology*; D011859:Radiography; D012307:Risk Factors; D012720:Severity of Illness Index; D013183:Sputum / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents