Active surveillance cultures of methicillin-resistant Staphylococcus aureus as a tool to predict methicillin-resistant S. aureus ventilator-associated pneumonia

Critical Care Medicine, 05/01/2012

Chan JD et al. – In the 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.

Methods

  • All patients ≥16yrs old admitted to the intensive care unit on mechanical ventilation ≥48hrs 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.
  • 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 7days afterward, and at intensive care unit discharge.

Results

  • 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).

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