Beneficial perspective on Staphylococcus epidermidis: a crucial species for skin homeostasis and pathogen defense

Human skin harbors a diverse microbiome that shapes immune function, protects against pathogens, and sustains tissue homeostasis. Among its dominant members, Staphylococcus epidermidis-a coagulase-negative staphylococcus-was long considered primarily an opportunistic pathogen, especially in the context of biofilm formation and implant-associated infections. However, emerging evidence reframes S. epidermidis as an active commensal, capable of controlling inflammation, supporting antimicrobial defenses, and stabilizing the cutaneous barrier. These dual roles are largely determined by its extensive strain-level heterogeneity and dynamic colonization strategies. Here, we review current progress in understanding the ecological versatility of S. epidermidis, with particular focus on its potential benefits, its diversity and colonization dynamics, and the balance of costs and benefits associated with its presence on human skin.