The skin microbiome Original paper

What was reviewed?

This article reviewed the structure, ecology, and clinical relevance of the human skin microbiome, framing the skin as a complex, living ecosystem rather than a passive barrier. The authors synthesized molecular, genomic, immunological, and clinical literature to explain how microbial communities are distributed across different skin sites and how these communities interact dynamically with host physiology and immunity. The review emphasized that microbial colonization is shaped by local skin microenvironments, including moisture, lipid content, pH, temperature, and oxygen availability, and that these ecological pressures consistently select for specific microbial communities. Using evidence from culture-independent sequencing studies, the paper reframed earlier culture-based assumptions. It demonstrated that the skin microbiome is far more diverse, variable, and functionally active than previously recognized. The review also integrated emerging data linking microbial imbalance to inflammatory skin disorders, infections, and impaired barrier function, positioning the skin microbiome as a key determinant of cutaneous health rather than a bystander.

Who was reviewed?

The review drew on studies involving healthy adult volunteers, infants, and patients with inflammatory and infectious skin conditions, including acne, atopic dermatitis, seborrhoeic dermatitis, psoriasis, chronic wounds, and device-associated infections. It incorporated data from human skin sampling across multiple anatomical sites, longitudinal studies tracking temporal stability, and experimental models examining host–microbe immune interactions. Rather than focusing on a single population, the authors synthesized findings across age groups, sexes, and disease states to identify consistent microbial patterns associated with health and pathology.

Most Important Findings

The most important findings establish that the skin microbiome is dominated by a small number of core bacterial groups whose relative abundance is dictated by skin site ecology. Major microbial associations include Propionibacterium (now Cutibacterium) species in sebaceous areas, Staphylococcus and Corynebacterium species in moist regions, and a more diverse mixture of Actinobacteria, Proteobacteria, Firmicutes, and Bacteroidetes in dry sites. The review highlighted Staphylococcus epidermidis as a key protective commensal with immunomodulatory and antimicrobial activity, capable of inhibiting pathogens such as Staphylococcus aureus through secreted peptides and synergy with host antimicrobial defenses. In contrast, dysbiosis characterized by S. aureus overgrowth was strongly associated with atopic dermatitis flares, reflecting impaired barrier function and reduced antimicrobial peptide production. The paper also emphasized the role of fungal members, particularly Malassezia species, as dominant residents of sebaceous skin with context-dependent pathogenic potential in seborrhoeic dermatitis. Importantly, the review underscored that microbial function, rather than mere presence, determines clinical impact, with commensals actively shaping immune tolerance, inflammation, and tissue repair.

Greatest Implication

The greatest implication for clinicians is that skin diseases cannot be fully understood or managed by targeting pathogens alone. The findings support a shift toward therapies that preserve or restore beneficial microbial functions, strengthen barrier integrity, and modulate host–microbiome immune signaling. This framework explains why broad-spectrum antimicrobials can worsen chronic skin conditions and highlights the therapeutic potential of microbiome-informed strategies, including selective antimicrobials, barrier repair, and promicrobial interventions.