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Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus MRSA
Published on: February 9, 2011
Methicillin-Resistant Staphylococcus aureus Nasal Swab Is Insufficient to Withhold Empiric Methicillin-Resistant
Kevin N Harrell1, Tyler Koestner2, Jacob Lloyd3
1Department of Surgery, University of Tennessee College of Medicine Chattanooga, Chattanooga, Tennessee.
Introduction:
Methicillin-resistant staphylococcus aureus (MRSA) nasal colonization is a predictor of MRSA pneumonia in intensive care unit (ICU) patients. Negative nasal swabs have shown up to a 97% negative predictive value for MRSA pneumonia in nontrauma populations, though little investigation has been pursued in trauma patients.
Materials And Methods:
All trauma patients admitted to the ICU from April 2018 to February 2019 were screened for MRSA colonization by nasal swab. Patients with suspicion for pneumonia underwent bronchoalveolar lavage or quantitative sputum culture and were started on empiric antibiotic therapy based on the swab result. Swab-positive patients were started on empiric MRSA coverage and swab-negative patients were not.
Results:
MRSA nasal swab screening was performed in 601 trauma ICU patients. Ninety-six patients subsequently underwent pneumonia workup and were started on an empiric antibiotic regimen based on nasal swab results. Seventeen (17.7%) patients were MRSA nasal swab positive on screening, and 22 (22.9%) patients subsequently had significant growth of MRSA on quantitative respiratory culture. The sensitivity of nasal swab was 50.0% and the specificity was 91.9%. Eleven patients had a negative MRSA nasal swab but a positive MRSA pneumonia (11.5%). Patients with inadequate antibiotic coverage had statistically longer hospital length of stay, ICU length of stay, ventilator days, and rates of unplanned intubation compared to patients with adequate antibiotic coverage.
Conclusions:
Nasal swab screening was not sensitive enough in a trauma population with a high endemic incidence of MRSA colonization to warrant withholding empiric antibiotic MRSA coverage in patients with suspected pneumonia.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) nasal swabs are not sensitive enough to rule out MRSA pneumonia in trauma patients. Inadequate antibiotic coverage for MRSA in these patients led to longer hospital stays and increased complications.
Area of Science:
- Infectious Diseases
- Critical Care Medicine
- Trauma Surgery
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization predicts MRSA pneumonia in intensive care unit (ICU) patients.
- Previous studies show high negative predictive value for MRSA pneumonia with negative nasal swabs in non-trauma populations.
- Limited research exists on MRSA nasal colonization's predictive value for pneumonia in trauma patients.
Purpose of the Study:
- To evaluate the accuracy of MRSA nasal swab screening in predicting MRSA pneumonia among trauma patients admitted to the ICU.
- To determine if negative MRSA nasal swabs can reliably exclude the need for empiric MRSA antibiotic coverage in trauma ICU patients with suspected pneumonia.
Main Methods:
- Prospective screening of 601 trauma ICU patients for MRSA colonization via nasal swab from April 2018 to February 2019.
- Patients with suspected pneumonia underwent bronchoalveolar lavage or quantitative sputum culture.
- Empiric antibiotic therapy was initiated based on nasal swab results; MRSA coverage was given to swab-positive patients only.
Main Results:
- Of 96 patients with pneumonia workup, 17.7% were MRSA nasal swab positive, and 22.9% had positive respiratory cultures for MRSA.
- Nasal swab sensitivity was 50.0% and specificity was 91.9%.
- Eleven patients (11.5%) had a negative nasal swab but positive MRSA pneumonia; these patients experienced longer hospital stays, ICU stays, ventilator days, and higher rates of unplanned intubation due to inadequate antibiotic coverage.
Conclusions:
- MRSA nasal swab screening lacks sufficient sensitivity in trauma ICU populations with high endemic MRSA colonization rates.
- Withholding empiric MRSA antibiotic coverage based solely on negative nasal swabs is not recommended for trauma patients with suspected pneumonia.
- Inadequate MRSA coverage in this population is associated with significantly worse clinical outcomes.
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