MRSA nasal PCR as a prevalence-dependent stewardship tool in hospitalized children: a structured review

INTRODUCTION: Empiric anti-methicillin-resistant Staphylococcus aureus (MRSA) therapy is common in hospitalized children with severe pneumonia or suspected sepsis. MRSA nasal polymerase chain reaction (PCR) is increasingly used to support de-escalation, but its central metric, the negative predictive value (NPV), is often quoted without the prevalence on which it depends. AREAS COVERED: PubMed, EMBASE, and the Cochrane Library were searched from January 2018 to April 2026. Twenty-seven sources were synthesized; the pediatric diagnostic-accuracy and stewardship studies and the in-window meta-analyses were appraised with QUADAS-2, EPOC, or AMSTAR-2. We examine why NPV is high in children, the prevalence above which a negative swab no longer rules out infection, performance by syndrome, and the pediatric implementation and cost literature, and propose a prevalence-conditioned framework for prospective evaluation. EXPERT OPINION: The pediatric evidence is observational, and no study was designed to test whether PCR-guided de-escalation is safe. A negative swab is a defensible rule-out aid in severe or complicated pneumonia and selected low-prevalence intensive care sepsis, but not in skin, soft-tissue, or osteoarticular infection. Because NPV depends on prevalence, programs should measure the proportion of children with the target syndrome who have culture-confirmed MRSA infection locally before applying a published NPV.