# Testing for methicillin-resistant Staphylococcus aureus in the anterior nares for antibiotic de-escalation in patients presenting with acute skin and soft tissue infections: systematic review and meta-analysis

## TL;DR

This study reviews how well checking for MRSA in the nose can predict MRSA infections in skin and soft tissue infections, finding it has high specificity but low sensitivity.

## Contribution

This is the first meta-analysis evaluating MRSA nares screening performance for predicting MRSA in acute skin and soft tissue infections.

## Key findings

- MRSA nares screening showed high specificity (0.949) but low sensitivity (0.474) for predicting MRSA infections in acute skin and soft tissue infections.
- The negative predictive value was 0.815 with a baseline MRSA prevalence of 29.1%.
- Sensitivity was higher in adults (0.543) compared to children (0.285).

## Abstract

To improve the understanding of appropriate antibiotic de-escalation and stewardship by consolidating the evidence on screening for methicillin-resistant Staphylococcus aureus (MRSA) colonization of the nares to predict MRSA in acute skin and soft tissue infections (SSTIs).

This meta-analysis was performed according to PRISMA guidelines. Six databases were searched by two reviewers for articles on MRSA detection in the nares and acute SSTIs. The quality and risk of bias of the articles were then assessed. The primary outcomes of interest were pooled sensitivity and specificity. Sub-analyses were also performed to test for heterogeneity.

After screening 1040 records, 15 articles (n = 1,970) were included in the meta-analysis. Using MRSA nares screening to predict MRSA in acute SSTIs had an overall specificity of 0.949 and sensitivity of 0.474. With a prevalence of 29.1%, the calculated NPV was 0.815. There were sub-analyses on various study variables, such as study location, participant age, and detection by polymerase chain reaction versus culture. The only significant finding was an increased sensitivity for adults (0.543) compared to pediatric participants (0.285).

To our knowledge, this is the first meta-analysis that focuses on the performance of MRSA nares screening for predicting MRSA infection in patients presenting with acute SSTIs. The baseline prevalence of MRSA SSTIs is important for interpreting the screening results, and the prevalence is influenced by geography and patient factors. This clinical context must be considered before utilizing MRSA nares screening for acute SSTIs.