The skin microbiome plays a role in the pathogenesis of atopic dermatitis. However, it is unclear whether the range of microbiota on the skin is the cause or consequence of atopic skin inflammation. The influence of new systemic therapies for the treatment of moderate to severe atopic dermatitis (such as biologics or Janus kinase inhibitors) on the skin microbiome is largely unknown. The main aim of this scientific exploratory study is to investigate whether and how the skin microbiome changes in patients with moderate to severe atopic dermatitis during systemic therapy. This not only allows new hypotheses to be generated on the pathogenesis of atopic dermatitis, but also new objective scales for the severity of atopic dermatitis can be developed.