Bacteria
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 one. 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.
| Organism | observations |
|---|---|
| Staphylococcus epidermidis | Common, occasionally pathogenic |
| Staphylococcus aureus | Infrequent, usually pathogenic |
| Staphylococcus warneri | Infrequent, occasionally pathogenic |
| Streptococcus pyogenes | Infrequent, usually pathogenic |
| Streptococcus mitis | Frequent, occasionally pathogenic |
| Propionibacterium acnes | Frequent, occasionally pathogenic |
| Corynebacterium spp. | Frequent, occasionally pathogenic |
| Acinetobacter johnsonii | Frequent, occasionally pathogenic |
| Pseudomonas aeruginosa | Infrequent, occasionally pathogenic |
Read more about this topic: Skin Flora, Species Variety
Famous quotes containing the word bacteria:
“To the eyes of a god, mankind must appear as a species of bacteria which multiply and become progressively virulent whenever they find themselves in a congenial culture, and whose activity diminishes until they disappear completely as soon as proper measures are taken to sterilise them.”
—Aleister Crowley (1875–1947)