MRSA nares PCR does not cut vancomycin duration in ICU CAPMRSA Testing Does Not Reduce Vancomycin Use in Pneumonia Patients
Clinical infectious diseases : an official publication of the Infectious Diseases Society of AmericaPublished September 6, 2026Study authors: Freiberg Jeffrey A, Qian Edward T, Nairon Kylie G, Ereshefsky Benjamin J, Hennessy Cassandra, Van Wi…PubMed ↗NCT06272994 ↗DOI ↗Editorial oversight: Dr. Amelia Tan, PhD · Internal Medicine & Chronic Disease
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Key Takeaway
Consider not relying on MRSA nares PCR to shorten vancomycin therapy in ICU CAP; it did not reduce duration or mortality.
This randomized controlled trial enrolled 277 adult ICU patients with suspected community-acquired pneumonia (CAP) at a single center. Patients were randomized to receive MRSA nares PCR testing after ICU admission or usual care. The primary outcome was vancomycin-free hours alive, with 30-day mortality as a secondary outcome. The study was non-blinded, and follow-up duration was not reported.
The negative predictive value of the MRSA PCR nasal swab was 98.9%. However, vancomycin-free hours alive were 105.7 hours in the control group versus 109.7 hours in the intervention group, an adjusted difference of 4 hours (95% CI, -9.5 to 18.2; P =.458). This difference was not statistically significant, indicating that PCR testing did not lead to a meaningful reduction in vancomycin exposure.
Safety outcomes, including adverse events and serious adverse events, were not reported. The study's main limitation is its non-blinded design, which may introduce bias in vancomycin management decisions. Funding and conflicts of interest were not reported.
In practice, MRSA nares PCR testing did not decrease the duration of vancomycin use or 30-day mortality among ICU patients with suspected CAP. Clinicians should not expect this testing strategy to substantially reduce vancomycin exposure in this population.
How this fits prior evidence
This trial contrasts with prior evidence on vancomycin use in different contexts. While oral vancomycin prophylaxis significantly reduces Clostridium difficile incidence in HSCT recipients, and intraosseous vancomycin reduces infection risk in TKA, this study found no benefit of MRSA nares PCR in reducing vancomycin duration for ICU CAP. It also does not align with the mortality benefits seen with corticosteroids in severe CAP, highlighting that diagnostic stewardship alone may not improve outcomes.
Researchers conducted a trial involving 277 adult patients in an intensive care unit. These patients were being treated for suspected community-acquired pneumonia. The study looked at whether using a specific PCR test to check for MRSA in the nose would allow doctors to use less of the antibiotic vancomycin.
The results showed that while the test was very accurate at identifying who did not have MRSA, it did not change how much vancomycin was used. Patients who received the test had an average of 109.7 vancomycin-free hours, while those who did not receive it had 105.7. This difference was not statistically significant.
Because the test did not reduce the duration of vancomycin use or the 30-day mortality rate, it may not change current treatment plans. This study was not blinded, which is a limitation to consider when looking at the results. Patients and doctors should discuss these findings with their medical team.
What this means for you:
MRSA nasal swab testing did not reduce the amount of vancomycin used for pneumonia in ICU patients.
Common questions
Does MRSA testing help reduce antibiotic use?
In this study of 277 ICU patients, MRSA nasal swab testing did not decrease the duration of vancomycin use. Patients who received the test had 109.7 vancomycin-free hours compared to 105.7 for those who did not. This difference was not statistically significant, meaning the test did not change how much antibiotic was used.
Is the MRSA nasal swab test accurate?
The study reported that the MRSA PCR nasal swab testing had a negative predictive value of 98.9 percent. This means the test was very effective at identifying patients who did not have MRSA. However, this high accuracy did not lead to a reduction in vancomycin use for pneumonia patients.
Did the test improve survival rates for pneumonia patients?
The study found that MRSA PCR nasal swab testing did not decrease the 30-day mortality rate among ICU patients with suspected community-acquired pneumonia. Because the results did not show a change in survival or antibiotic duration, the test may not change current treatment practices.
BACKGROUND: Fear of methicillin-resistant Staphylococcus aureus (MRSA) as a cause of community-acquired pneumonia (CAP) frequently leads to empiric vancomycin coverage. Data evaluating the use of MRSA polymerase chain reaction (PCR) nasal swab testing to guide vancomycin de-escalation is limited for patients in the intensive care unit (ICU).
METHODS: Swab Testing to Optimize Pneumonia Treatment With Empiric Vancomycin (STOP-Vanc) is a pragmatic, prospective, single-center, non-blinded randomized trial in which adult ICU patients with suspicion of CAP were randomized 1:1 to receive usual care either with (intervention) or without (control) the addition of MRSA nares PCR testing following ICU admission. The primary outcome was vancomycin-free hours alive, defined as the expected number of hours alive and free of vancomycin use within the first 7 days of trial enrollment as estimated using a longitudinal proportional odds state transition model adjusted for baseline covariates.
RESULTS: A total of 277 adult ICU patients were randomized. Methicillin-resistant Staphylococcus aureus PCR nasal swab testing had a negative predictive value (NPV) of 98.9% in the intervention arm. The primary endpoint, vancomycin-free hours alive, was 105.7 in the control arm and 109.7 in the intervention arm (adjusted difference, 4 hours; 95% CI, -9.5-18.2; P = .458).
CONCLUSIONS: Despite MRSA PCR nasal swab testing demonstrating a high NPV in this critically ill population, MRSA PCR nasal swab testing did not decrease the duration of vancomycin use or 30-day mortality among ICU patients with suspected CAP. Additional clinician education and antimicrobial stewardship interventions might be needed to reduce vancomycin use in this patient population.
CLINICAL TRIALS REGISTRATION: ClinicalTrials.gov NCT06272994 (STOP-Vanc).
