A review of topical probiotic therapy for atopic dermatitis.

Atopic dermatitis (AD) is a common, chronic skin disorder that is associated with dysbiosis of the skin microbiome along with an impaired skin barrier and abnormal immune signalling. Particularly, AD has been associated with increased abundance of Staphylococcus aureus and decreased overall bacterial diversity. Topical probiotic formulations are garnering further interest in the treatment of AD and may be derived from commensal bacteria found on healthy epithelium or from exogenous bacteria. Strains chosen for clinical trials have often demonstrated antimicrobial actions to S. aureus in vitro. Multiple randomized clinical trials with topical probiotics have resulted in significant improvements in clinical severity, decreased abundance of S. aureus in treated lesional skin and increased bacterial diversity. Side-effects from available studies have been minimal apart from one patient who developed a furuncle in the treatment area. Topical probiotics have been shown to be safe and potentially efficacious in AD; however, further research including larger, longer-term clinical trials need to be performed before topical probiotics should be recommended to patients.