The skin is composed of and covered with hundreds of species of living microorganisms, in accordance with a well-defined organization: the cutaneous microbiota.
A disruption in this equilibrium can result in skin disease.
The cutaneous microbiota is a very complex ecosystem, composed of an ensemble of living microorganisms (bacteria, fungi, viruses, and parasites), which contribute to the olfactory signature of human skin. It has several functions; it plays a defensive role, acts as a cutaneous barrier, and acts as a regulator for the immune system.
An individual’s microbiota is constituted at birth: from contact with the vaginal flora after a vaginal birth, or from contact with stomach flora in the case of a Caesarean section. This cutaneous microbiota evolves progressively, varying from one individual to another based on age (birth, puberty, aging), sex (male, female), genetic factors, physiochemical factors (humidity, pH, temperature, fat content of the skin), environment (climate, geographical area), lifestyle (hygiene, cosmetic products, socioeconomic conditions, etc.), immune status, the existence of disease, and whether a person is taking medications, etc. It also differs within a single person, based on location (face, armpits, back, etc.). Imbalance is associated with dermatological diseases like acne, psoriasis, and atopic dermatitis. Understanding the cutaneous microbiota’s involvement in the mechanisms that cause certain skin diseases may lead to better treatment.