Title: Evaluation of Pediatric Pharmacy Driven Methicillin Resistant Staphylococcus Aureus (MRSA) Nasal Polymerase Chain Reaction (PCR) protocol Authors: Beth Addington, PharmD, BCPPS, Sarah Withers, PharmD, MS, BCIDP, Rachel Samples, PharmD, MBA Objective: To evaluate the impact of a pediatric pharmacy-driven MRSA nasal PCR protocol on the duration of anti-MRSA antibiotic therapy in pediatric patients before and after protocol implementation. Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a significant cause of pediatric infections. Current Infectious Diseases Society of America guidelines recommend MRSA nasal polymerase chain reaction (PCR) screening as a de-escalation tool for anti-MRSA therapy, given its high negative predictive value. While pharmacist involvement in antimicrobial stewardship has demonstrated benefits, limited data exist on pediatric pharmacy-driven MRSA nasal PCR protocols. Methods: A single-center, pre- and post-interventional, retrospective cohort study included pediatric patients who received MRSA nasal PCR testing during two study periods: March 1–July 31, 2024 (pre-implementation) and March 1–July 31, 2025 (post-implementation). The primary outcome was the median duration of anti-MRSA antibiotic therapy before versus after protocol implementation. Secondary outcomes included pharmacist-ordered or documented MRSA PCRs, duration of intravenous antibiotic therapy, hospital length of stay, escalation of care, suspected or confirmed infection types, empiric and oral antibiotic selection, culture acquisition and results, and diagnostic performance of MRSA nasal PCRs, including sensitivity, specificity, positive predictive value, and negative predictive value. Results: A total of 283 patients were included (pre-intervention n=134; post-intervention n=149). Median duration of intravenous anti-MRSA therapy was unchanged (1 [IQR 1–2] vs 1 [1–1] days; p=0.90). However, total MRSA antibiotic duration decreased (2 [1–6] vs 1 [1–5] days; p=0.01), as did total antibiotic duration (9 [7–14] vs 8 [6–12] days; p=0.02). Hospital length of stay was also reduced (median 3 vs 2 days; p<0.01). No significant differences were observed in culture acquisition, MRSA isolation rates, surgical interventions, or rates of therapy de-escalation. The MRSA PCR demonstrated high NPV (93.2% overall; 96.7% for pneumonia) but lower positive predictive value (PPV) (66.6% for SSTI; 20.0% for pneumonia). Conclusion: Implementation of a pediatric pharmacy-driven MRSA nasal PCR protocol was associated with reductions in total MRSA and overall antibiotic duration, as well as shorter hospital length of stay, without adversely affecting clinical outcomes. These findings support the role of pharmacists in antimicrobial stewardship initiatives and highlight the clinical utility of MRSA PCR testing in pediatric populations.
