Skin flora

Skin flora, also called skin microbiota, refers to microbiota (communities of microorganisms) that reside on the skin, typically human skin.

Many of them are bacteria of which there are around 1,000 species upon human skin from nineteen phyla.^[1][2] Most are found in the superficial layers of the epidermis and the upper parts of hair follicles.

Skin flora is usually non-pathogenic, and either commensal (are not harmful to their host) or mutualistic (offer a benefit). The benefits bacteria can offer include preventing transient pathogenic organisms from colonizing the skin surface, either by competing for nutrients, secreting chemicals against them, or stimulating the skin's immune system.^[3] However, resident microbes can cause skin diseases and enter the blood system, creating life-threatening diseases, particularly in immunosuppressed people.^[3]

A major non-human skin flora is Batrachochytrium dendrobatidis, a chytrid and non-hyphal zoosporic fungus that causes chytridiomycosis, an infectious disease thought to be responsible for the decline in amphibian populations.^[4]