Hand eczema and changes in the skin microbiome after 2 weeks of topical corticosteroid treatment

Background: More than 50% of patients with hand eczema (HE) are colonized with Staphylococcus aureus. Comprehensive knowledge of the skin microbiome and its changes in patients with HE may provide insights into future potential therapeutical targets. Objective: To describe the skin microbiome in patients with moderate-to-severe chronic HE and assess its changes following treatment with topical corticosteroids (TCS). Methods: Bacterial samples were collected from lesional and nonlesional skin before and after 2 weeks of TCS treatment using ESwabs and analysed by 16S rRNA and tuf gene sequencing. Clinically, the disease severity was assessed by the Hand Eczema Severity Index (HECSI). Results: A cohort of 31 patients with HE were included and followed up. Compared to nonlesional skin, lesional skin differed in overall bacterial community composition (p = 0.02), displayed higher relative abundance of Staphylococcus, in particular S. aureus (p = 0.01) and lower abundance of Micrococcus (p = 0.02). As disease severity improved with treatment, these microbial characteristics on lesional skin shifted towards that of nonlesional skin on the hands. Conclusions: The bacterial skin microbiome was altered in lesions of HE and partly driven by S. aureus colonization, however, shifted towards nonlesional skin following treatment. Our results emphasize the future possibilities for anti-S. aureus treatment strategies.