MSA

Mannitol Salt Agar
This is a plate media created with mannitol as the primary carbon source, phenol red as an indicator dye and has sodium chloride added to discourage most gram negative growth. Byproducts of mannitol fermentation will drop the pH of the media around colonies and turn the media yellow. This media is often used to distinguish Staphylococcus aureus from other varieties of Staph.