Region specific utility of MRSA nares screening in patients with diabetic foot cultures across the United States

Background Methicillin-resistant Staphylococcus aureus (MRSA) remains a critical pathogen in diabetic foot infections (DFIs), contributing to prolonged hospitalizations, and morbidity. MRSA nares colonization screening has shown utility in the negative predictive (NPV) value of MRSA infections, though its role in DFIs remains under-characterized. Methods This retrospective cohort study analyzed 57,213 hospitalized patients with DFIs across 9 U.S. census regions to evaluate implications of MRSA nares screening for DFIs and to assess regional variations in outcomes. NPV was calculated regionally. Multivariable logistic regression assessed independent predictors of 30-day mortality. Results MRSA wound culture positivity ranged from 16.1–24.3%. NPV ranged from 86.4% (East South-Central region) to 91.7% (West North Central region), with most regions clustering between 88% and 91%. MRSA nares positivity was associated with 38% increased odds of 30-day mortality (OR 1.38, 95%CI 1.23–1.56). Conclusions MRSA nares screening demonstrates high NPV across all regions, supporting its role as a valuable tool for de-escalating empiric anti-MRSA therapy in DFIs. Its limited PPV necessitates confirmatory cultures for positive cases. MRSA nares colonization also serves as an independent predictor of short-term mortality, suggesting its potential use in prognostic risk stratification.