Targeted Antimicrobial Stewardship in a Pediatric Intensive Care Unit: Using the Methicillin‐Resistant Staphylococcus aureus ( MRSA ) Nasal Polymerase Chain Reaction ( PCR ) to Reduce Vancomycin Days of Therapy

BACKGROUND: Vancomycin is commonly used in pediatric intensive care units (PICUs) to treat methicillin-resistant Staphylococcus aureus (MRSA) infections. While previous interventions in children's hospitals have successfully targeted vancomycin use, few have incorporated MRSA nasal polymerase chain reaction (PCR) testing. The MRSA PCR has been shown to reliably rule out MRSA infection and reduce vancomycin therapy duration in adults, but data in children are limited. This study aimed to evaluate the impact of an antimicrobial stewardship intervention on vancomycin use. METHODS: This retrospective study included patients less than 18 years old who received vancomycin in the PICU between January 1, 2019 and June 30, 2024. The primary outcome was vancomycin days of therapy (DOT) before and after the antimicrobial stewardship intervention. Secondary outcomes included acute kidney injury (AKI), hospital length of stay, and MRSA PCR sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). RESULTS: A total of 251 patients were included, with 126 in the pre-group and 125 in the post-group. The median age was 2 years, and 60% were mechanically ventilated. The most common indication for vancomycin was sepsis of unknown origin (47%). The median vancomycin DOT was 4 days in both groups (p = 0.033). In patients without confirmed MRSA infection, the median duration was shorter in the post-group (4 vs. 3 days, p = 0.009). More patients in the post-group had vancomycin discontinued at 72 h (38.9% vs. 61.6%, p < 0.001). No significant differences were observed in secondary outcomes. The MRSA PCR sensitivity, specificity, PPV, and NPV were 66.7%, 92.7%, 34.5%, and 98.3%, respectively. CONCLUSIONS: This intervention in PICU patients at an academic medical center led to more rapid vancomycin discontinuation and shorter DOT. The MRSA PCR demonstrated a high NPV, supporting its use as an antimicrobial stewardship tool.