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Updated: May 23, 2026
Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria
Published on: May 8, 2013
Active surveillance cultures of methicillin-resistant Staphylococcus aureus as a tool to predict
Jeannie D Chan1, Timothy H Dellit, Julie A Choudhuri
1Department of Pharmacy, Harborview Medical Center and School of Pharmacy, University of Washington, Seattle, WA, USA. jdchan@u.washington.edu
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.
Design:
Prospective observational study.
Setting:
Eighty-nine-bed surgical and medical intensive care units in a university-affiliated urban teaching hospital and level I trauma and burn center.
Patients:
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.
Interventions:
None.
Measurements And Main 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.
Insights
Weekly surveillance cultures for methicillin-resistant Staphylococcus aureus (MRSA) colonization accurately predict MRSA ventilator-associated pneumonia (VAP). A negative surveillance culture can effectively rule out MRSA VAP, potentially reducing empirical antibiotic use.
Area of Science:
- Infectious Diseases
- Critical Care Medicine
- Microbiology
Background:
- Ventilator-associated pneumonia (VAP) is a common intensive care unit (ICU) infection.
- Methicillin-resistant Staphylococcus aureus (MRSA) is a frequent cause of VAP.
- Predicting MRSA VAP is crucial for effective patient management.
Purpose of the Study:
- To evaluate the performance of weekly active surveillance cultures in predicting MRSA VAP.
- To determine the sensitivity, specificity, and predictive values of MRSA colonization screening.
Main Methods:
- Prospective observational study in a university-affiliated hospital ICU.
- Included patients on mechanical ventilation for ≥48 hours with VAP diagnosis.
- Weekly surveillance cultures (nares, oropharynx, trachea, wounds) and respiratory cultures were performed.
Main Results:
- 388 patients with VAP were included; 9.5% had MRSA VAP.
- Prior MRSA colonization was detected in 13.9% of patients.
- Sensitivity for predicting MRSA VAP was 70.3%, specificity 92.0%.
- Negative predictive value was high at 96.7%.
Conclusions:
- Once-weekly active surveillance for MRSA colonization demonstrates high specificity and negative predictive value.
- Negative surveillance cultures can reliably exclude MRSA as a cause of VAP.
- This approach may reduce the need for empirical MRSA treatment in VAP patients.
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