Dupilumab Sustains Long-Term Reduction of S. aureus in People with AD: Daily Dose

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On June 6, 2025, we reported on a study presented at the 2025 Revolutionizing Atopic Dermatitis (RAD) Conference that found dupilumab therapy leads to sustained reductions in Staphylococcus aureus (S. aureus) colonization in both lesional and non-lesional skin of participants with atopic dermatitis (AD) after 1 year of treatment.

The study

The study, conducted at the University of Rochester Medical Center, evaluated 5 participants with moderate-to-severe AD enrolled in a longitudinal observational trial. All participants were colonized with viable S. aureus at baseline, with lesional bacterial counts ranging from 3 813 to 115 000 CFU/cm² and non-lesional counts from 3 to 48 750 CFU/cm².

The findings

After 12 to 18 months of continuous dupilumab therapy, S. aureus abundance was undetectable in 4 of 5 participants (80%) at both lesional and non-lesional sites. In the remaining participant—who had the highest initial burden—counts were reduced by several orders of magnitude to 48 CFU/cm² (lesional) and 2 CFU/cm² (non-lesional), accompanied by a drop in Eczema Area and Severity Index (EASI) from 15.2 to 6.6.

All participants experienced at least a 7-point reduction in EASI score (median [IQR]: 9.8 [8.0, 20.4]). Notably, one patient (ID 4) maintained a high EASI of 26.4 at one year but showed complete clearance of S. aureus, indicating that microbial reductions may occur independently of full clinical remission.

Authors' comments

“Future studies will focus on whether this reduction is maintained with longer durations of dupilumab treatment. We will also address whether this reduction is sustained when dupilumab is discontinued and how abundance reflects changes in AD severity off treatment.”

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