page_title: Skin flora
section_title: Bacteria
hierarchical_section_title: Skin flora / Species variety / Bacteria
caption_attribution_description: English: Scanning Electron Micrograph of Staphylococcus epidermidis
context_page_description: The term skin flora refers to the microorganisms which 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. 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 or mutualistic. 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. However, resident microbes can cause skin diseases and enter the blood system, creating life-threatening diseases, particularly in immunosuppressed people.
  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.
context_section_description: The estimate of the number of species present on skin bacteria has been radically changed by the use of 16S ribosomal RNA to identify bacterial species present on skin samples direct from their genetic material. Previously such identification had depended upon microbiological culture upon which many varieties of bacteria did not grow and so were hidden to science.
  Staphylococcus epidermidis and Staphylococcus aureus were thought from cultural based research to be dominant. However 16S ribosomal RNA research finds that while common, these species make up only 5% of skin bacteria. However, skin variety provides a rich and diverse habitat for bacteria. Most come from four phyla: Actinobacteria (51.8%), Firmicutes (24.4%), Proteobacteria (16.5%), and Bacteroidetes (6.3%).
  There are three main ecological areas: sebaceous, moist, and dry. Propionibacteria and Staphylococci species were the main species in sebaceous areas. In moist places on the body Corynebacteria together with Staphylococci dominate. In dry areas, there is a mixture of species but b-Proteobacteria and Flavobacteriales are dominant. Ecologically, sebaceous areas had greater species richness than moist and dry ones. The areas with least similarity between people in species were the spaces between fingers, the spaces between toes, axillae, and umbilical cord stump. Most similarly were beside the nostril, nares (inside the nostril), and on the back.
caption: Scanning electron microscope image of Staphylococcus epidermidis one of roughly a thousand bacteria species present on human skin. Though usually not pathogenic, it can cause skin infections and even life-threatening illnesses in those that are immunocompromised.
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