Staphylococcus epidermidis
Plain-English definitions of microbiome research vocabulary — the terms you'll see across articles, testing services, and probiotic claims.
One of the most abundant commensal bacteria on human skin. S. epidermidis produces antimicrobial peptides that inhibit pathogenic bacteria including S. aureus, communicates with the immune system, and helps maintain the skin's acidic pH. Often called the "good staph."
Related terms
Staphylococcus aureus
A common bacterium that colonises the skin and nasal passages. While often harmless, S. aureus is an opportunistic pathogen implicated in wound infections, food poisoning, and skin conditions. In eczema, S. aureus overgrowth during flares is a consistent finding, driving inflammation through superantigen production.
Commensal
An organism that benefits from a relationship with another organism without causing harm. Most gut bacteria are commensals — they gain food and shelter while contributing to digestion, immunity, and barrier function.