935 Skin microbiome change in a prurigo pigmentosa patient successfully treated with oral minocycline

Prurigo pigmentosa (PP) is a rare inflammatory skin disease of unknown etiology presenting as a pruritic eruption of reticulated and symmetric macules and papules with the predilection for young females. Oral minocycline is effective to treat PP but the exact mechanism how minocycline improves PP still needs to be clarified. Since minocycline has an antibiotic property, we hypothesized that minocycline treatment might have some impacts on host resident bacteria, which may lead to the improvement of PP skin symptoms. Shift in microbiome composition has been reported to play important roles in the pathogenesis of skin inflammatory skin disorders such as atopic dermatitis and acne vulgaris and to be associated with disease severity. However, there are no reports evaluating the connection between the skin microbiome and the etiology of PP. To this end, we evaluated skin microbiome change of an 18-year-old Japanese female PP patient who was successfully treated with oral minocycline. Skin microbiome composition of the patient before and after minocycline treatment were analyzed by 16s rRNA sequencing. The results showed that four weeks of minocycline treatment decreased the percentage of Firmicutes and increased the percentage of Proteobacteria in the lesion skin. Among Firmicutes, the percentage of Staphylococcus epidermidis was markedly decreased after the treatment. This result suggests that oral minocycline treatment alter skin microbiome composition which might improve skin manifestations of PP. Although this is only a single case study and further case accumulation and investigation are necessary, our results suggest that the skin microbiome may be involved in the improvement of PP by oral minocycline administration.