Methicillin-resistant Staphylococcus aureus nasal swabs predict need for antibiotic coverage in a trauma population

Methicillin-resistant Staphylococcus aureus (MRSA) nasal swab screening in a general intensive care unit population has been shown to have a high negative predictive value (NPV) and is used to guide antibiotic stewardship. Trauma populations may be more susceptible to hospital-acquired pneumonia. The purpose of this study is to assess the utility of the MRSA nasal swab in predicting MRSA pneumonia in a trauma population. We hypothesize that the NPV of MRSA nasal swabs in the trauma population will be sufficient to rule out MRSA ventilator-associated pneumonia and therefore withhold MRSA empiric antibiotic treatment.

A retrospective review of trauma intensive care unit patients who received an MRSA nasal swab from 2020 to 2023 was performed. Positive and negative MRSA nasal swab groups were compared, and sensitivity, specificity, positive predictive value, and NPV were calculated. Methicillin-resistant S. aureus pneumonia was defined as the presence of ≥10 5 MRSA colonies on respiratory culture.

A total of 163 patients were screened, and 22 patients (13.5%) had positive MRSA nasal swabs. There were no significant differences in age, body mass index, smoking, or chronic obstructive pulmonary disease between the swab positive and swab negative groups. Sensitivity and specificity were 66.7% and 91.8%, respectively, with a positive predictive value of 45.4% and NPV of 96.4%. Five patients (3.1%) developed MRSA pneumonia, and all but one of these had a positive MRSA nasal swab. Area under the curve for the MRSA nasal test was calculated to be 0.793.

This is one of the largest studies to date to examine the utility of the MRSA nasal swab in the trauma population. The high NPV (96.5%) for the prediction of MRSA culture growth and ventilator-associated pneumonia suggests that MRSA nasal swabs may be a useful tool for antibiotics stewardship in the trauma population. ( J Trauma Acute Care Surg . 2026;100: 901-905. © 2026 American Association for the Surgery of Trauma.).

Retrospective Cohort Study, Therapeutic Care/Management; Level IV.