Abstract
BACKGROUND: The importance of the skin microbiome in the pathogenesis of atopic dermatitis (AD) is gaining increasing attention in current research and offers opportunities for new innovative treatment options. OBJECTIVES: This study investigated the efficacy of a probiotic bath additive on clinical symptoms and skin microbiome of patients with AD. MATERIALS AND METHODS: The study was randomized and double-blind: 22 patients applied a 10-min partial bath with 4.5 × 10(9) or 9 × 10(9) colony-forming units (CFU) of viable lactic acid bacteria per liter daily over a period of 14 days. The clinical symptoms were documented using the SCORing Atopic Dermatitis (SCORAD) index and a patient questionnaire at day 0, day 7 and day 14. In addition, skin swabs were taken for subsequent nucleic acid extraction for quantitative Staphylococcus aureus polymerase chain reaction and microbiome analysis using amplicon sequencing. RESULTS: Comparable efficacy was documented in both treatment groups: Probiotic baths with a concentration of 4.5-9 × 10(9) CFU/liter led to a significant reduction in SCORAD scores (start of study: 63.04) and local SCORAD (14.68) on day 7 (SCORAD 47.09, local SCORAD 10.99) and day 14 (SCORAD 35.26, local SCORAD 8.54). Furthermore, the patient-assessed parameters skin dryness and itching improved significantly over the treatment period. At the same time, the mean gene copy number of S. aureus decreased by about 83% and microbiome analyses showed an increase in the richness of the bacterial community. CONCLUSIONS: Topical application of a probiotic bath represents a promising supportive treatment option for AD that alleviates existing dysbiosis.