title: Polyclonal endemicity of Acinetobacter baumannii in ventilated patients in an intensive care unit in Uruguay.
abstract: OBJECTIVE
  To identify the mechanisms responsible for respiratory infections by Acinetobacter baumannii in intubated patients and risk factors for digestive colonization and infection by A. baumannii.
  
  
  METHODS
  We conducted a prospective study in an intensive care unit (ICU) between May 2005 and November 2006, including 175 consecutive patients at the beginning of invasive ventilation (day 1). We performed pharyngeal and rectal swabs on days 1, 4, 7, 10, 13, and 16. Respiratory samples were taken on days 1 and 7, or on suspicion of ventilator-associated pneumonia (VAP).
  
  
  RESULTS
  We detected 62 patients with A. baumannii digestive colonization and 20 cases of A. baumannii lower respiratory infection (14 VAP and six purulent tracheobronchitis (PTB)). Digestive colonization by A. baumannii was an independent risk factor for lower respiratory tract infections with that microorganism (p<0.0001; relative risk 8.71, 95% confidence interval 2.73-27.77). Respiratory and rectal A. baumannii isolates from the same patients were compared by enterobacterial repetitive intergenic consensus (ERIC)-PCR; in 9/11 cases (eight VAP and one PTB) results suggested events of exogenous pneumonia with previous colonization, whereas the remaining two cases (two PTB) were suggestive of exogenous infection without previous colonization.
  
  
  CONCLUSIONS
  In our unit the pathogenesis of VAP by A. baumannii is mixed, most cases corresponding to exogenous pneumonia with previous colonization.
authors: Cátedra de Enfermedades Infecciosas, Instituto de Higiene, Facultad de Medicina, Universidad de la República, Av. Alfredo Navarro 3051, Montevideo, 11600, Uruguay. jcmedina@fmed.edu.uy
authors: Julio Cesar
authors: JC
authors: Medina-Presentado
authors: Verónica
authors: V
authors: Seija
authors: Rafael
authors: R
authors: Vignoli
authors: Julio
authors: J
authors: Pontet
authors: Luciana
authors: L
authors: Robino
authors: Nicolás F
authors: NF
authors: Cordeiro
authors: Inés
authors: I
authors: Bado
authors: Virginia
authors: V
authors: García-Fulgueiras
authors: Maximiliano
authors: M
authors: Berro
authors: Cristina
authors: C
authors: Bazet
authors: Eduardo
authors: E
authors: Savio
authors: Gloria
authors: G
authors: Rieppi
mesh_terms: D000151:Acinetobacter Infections / Q000453:epidemiology* / Q000209:etiology*; D040981:Acinetobacter baumannii / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D000328:Adult; D000368:Aged; D003428:Cross Infection; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012140:Respiratory Tract Diseases / Q000453:epidemiology / Q000382:microbiology; D012307:Risk Factors; D014583:Uruguay; D012122:Ventilators, Mechanical / Q000009:adverse effects*