The skin microbiome: from historical ecology to therapeutic frontiers

BACKGROUND: Human skin, the body's largest organ, hosts a diverse ecosystem of bacteria, fungi, viruses, and mites collectively known as the skin microbiome. This microbiome supports cutaneous homeostasis through barrier defense, immune education, and metabolic functions. OBJECTIVE: To narratively review the historical evolution of skin microbiome research, synthesize current knowledge on its composition, biogeography, and functional roles in health and disease, and highlight emerging microbiome-based therapeutic strategies in dermatology. METHODS: This review integrates seminal historical works with contemporary evidence from culture-independent sequencing and multi-omic investigations of the skin microbiome, identified through a selective search of recent dermatology and microbiome literature. RESULTS: Modern molecular and multi-omic approaches have revealed microbial diversity across sebaceous, moist, and dry skin niches and clarified key functions of the skin microbiome, including colonization resistance, immune modulation, metabolite production, and participation in the gut-skin axis. Dysbiosis of these communities is linked to inflammatory conditions such as atopic dermatitis, acne vulgaris, psoriasis, and chronic wounds. A growing body of work supports microbiome-targeted interventions, including probiotics, prebiotics, postbiotics, and microbiome engineering, as promising personalized strategies. STUDY LIMITATIONS: As a narrative review, this work may be subject to selection bias and does not provide a quantitative synthesis of all available studies on the skin microbiome. CONCLUSIONS: By integrating historical context with mechanistic insights from modern microbiome research, this review underscores the skin microbiome as a central ecological determinant of cutaneous health and disease and provides a framework for translating microbiome science into clinical applications and precision dermatology.