Association between Staphylococcus aureus colonization and clinical improvement in pediatric atopic dermatitis treated with dupilumab: a pilot study

Background Moderate-to-severe atopic dermatitis (AD) in children is characterized by impaired skin barrier function, type 2 inflammation, and frequent Staphylococcus aureus colonization, contributing to disease severity and risk of superinfection. Dupilumab, an anti–IL-4/IL-13 receptor monoclonal antibody, improves clinical outcomes in pediatric AD, but longitudinal data on culture-based skin and nasal microbial changes remain limited. Objective To assess dupilumab efficacy in children with moderate-to-severe AD unresponsive to conventional therapy and to describe skin and nasal microbial colonization patterns at the 12-month time point compared with moderate AD receiving conventional topical therapy and healthy controls. Methods Prospective observational study. Children aged 6–16 years were enrolled in three groups: (a) moderate-to-severe AD starting dupilumab (assessments at baseline, 3, 6, and 12 months); (b) moderate AD receiving conventional topical therapy not eligible for biologic therapy; and (c) age-matched healthy controls. Outcomes included Eczema Area and Severity Index (EASI), Children’s Dermatology Life Quality Index (C-DLQI), and Peak Pruritus Numerical Rating Scale (NRS). At 12 months, nasal and skin e-Swabs were cultured; isolates were identified by MALDI-TOF with antimicrobial susceptibility testing. Longitudinal changes were analyzed using the Friedman test ( p < 0.05). Results Ten dupilumab-treated children (mean age 13 years; 60% males) showed rapid and sustained improvement in C-DLQI (median 13.5 to 3 at 3 months; 3.5 at 12 months), EASI (24.5 to 5.65 at 3 months, 1.2 at 12 months), and pruritus (NRS 10 to 4.5 at 3 months; 5.5 at 12 months). No adverse events or discontinuations occurred. At 12 months, nasal S. aureus colonization was detected in 2/10 dupilumab-treated patients versus 4/10 moderate AD receiving conventional topical therapy and 1/10 controls; skin S. aureus was absent in dupilumab-treated patients but present in 8/10 children with moderate atopic dermatitis receiving conventional topical therapy and 0/10 controls. Conclusion Dupilumab provides sustained clinical benefit and, in this cross-sectional assessment of a small pilot cohort, is associated with lower S. aureus colonization and the presence of commensal staphylococci in pediatric atopic dermatitis.