title: Active surveillance cultures of methicillin-resistant Staphylococcus aureus as a tool to predict methicillin-resistant S. aureus ventilator-associated pneumonia.
abstract: OBJECTIVE
  Ventilator-associated pneumonia is one of the most common infections in the intensive care unit and methicillin-resistant Staphylococcus aureus has emerged as a common cause of ventilator-associated pneumonia. We sought to study the performance characteristics of once weekly active surveillance culture of methicillin-resistant S. aureus colonization in predicting the development of methicillin-resistant S. aureus ventilator-associated pneumonia.
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  Eighty-nine-bed surgical and medical intensive care units in a university-affiliated urban teaching hospital and level I trauma and burn center.
  
  
  METHODS
  All patients≥16 yrs old admitted to the intensive care unit on mechanical ventilation≥48 hrs who met diagnostic criteria for ventilator-associated pneumonia by quantitative lower respiratory tract cultures obtained through bronchoscopic alveolar lavage or brush specimen between January 2008 and October 2010 were included.
  
  
  METHODS
  None.
  
  
  RESULTS
  Nine hundred twenty-four episodes of suspected ventilator-associated pneumonia were evaluated, and 388 patients with bronchoalveolar lavage-confirmed ventilator-associated pneumonia were included. Surveillance cultures were taken from the nares, oropharynx or trachea, and any open wound routinely on admission to the intensive care unit, every 7 days afterward, and at intensive care unit discharge. Of the 388 patients, 37 (9.5%) had methicillin-resistant S. aureus ventilator-associated pneumonia and 54 (13.9%) had methicillin-resistant S. aureus colonization documented by active surveillance culture before the development of ventilator-associated pneumonia. The sensitivity and specificity of prior methicillin-resistant S. aureus colonization as a predictor for methicillin-resistant S. aureus ventilator-associated pneumonia are 70.3% (95% confidence interval [CI] 52.8-83.6) and 92.0% (95% CI 88.5-94.5), respectively. The positive and negative predictive values are 48.1% (95% CI 34.5- 62.0) and 96.7% (95% CI 94.0-98.3).
  
  
  CONCLUSIONS
  In our study, prior methicillin-resistant S. aureus colonization as ascertained by once-weekly active surveillance culture yielded high specificity and negative predictive value, suggesting that negative active surveillance culture can accurately exclude methicillin-resistant S. aureus as an etiology in most patients with ventilator-associated pneumonia and may decrease the need for empirical methicillin-resistant S. aureus coverage in patients with suspected ventilator-associated pneumonia.
authors.affiliation: Department of Pharmacy, Harborview Medical Center and School of Pharmacy, University of Washington, Seattle, WA, USA. jdchan@u.washington.edu
authors.forename: Jeannie D
authors.initials: JD
authors.lastname: Chan
authors.forename: Timothy H
authors.initials: TH
authors.lastname: Dellit
authors.forename: Julie A
authors.initials: JA
authors.lastname: Choudhuri
authors.forename: Elizabeth
authors.initials: E
authors.lastname: McNamara
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Melius
authors.forename: Heather L
authors.initials: HL
authors.lastname: Evans
authors.forename: Joseph
authors.initials: J
authors.lastname: Cuschieri
authors.forename: Saman
authors.initials: S
authors.lastname: Arbabi
authors.forename: John B
authors.initials: JB
authors.lastname: Lynch
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018893:Bronchoalveolar Lavage; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D011023:Pneumonia, Staphylococcal / Q000175:diagnosis* / Q000382:microbiology; D053717:Pneumonia, Ventilator-Associated / Q000175:diagnosis* / Q000382:microbiology; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D055815:Young Adult