The Skin Microbiota

The skin hosts a diverse community of microbes, including bacteria and fungi.

Microbial composition varies across different body areas due to varying moisture and oil levels.

Oily areas, like the forehead, are dominated by Cutibacterium acnes.

These bacteria feed on sebum and produce propionic acid, that lowers the skin’s pH and restricts pathogen growth.

Moist and oily sites, like the scalp, also support fungi such as Malassezia furfur. In susceptible individuals, host inflammatory responses to fungal metabolites lead to dandruff formation.

Moist areas such as the armpits harbor species of staphylococci and corynebacteria.

These bacteria metabolize components of sweat and produce antimicrobial compounds that inhibit harmful microbes.

Dry areas, like the forearms, contain bacteria from major phyla, including Actinobacteriota, Bacteroidota, Pseudomonadota, and Bacillota.

In these regions, Staphylococcus epidermidis produces antimicrobial peptides like bacteriocins, which inhibit pathogens and help maintain skin health.