This type of medium is both selective and differential. The MSA will select for organisms such as Staphylococcus species which can live in areas of high salt concentration (plate on the left in the picture below).

Is MSA a differential medium or a selective medium or both or neither?

Mannitol Salt Agar (MSA)

This is a medium that is both selective and differential. The high salt concentration (7.5%) is the selective ingredient. Staphylococcus species, which commonly inhabit human skin, can grow on this high salt concentration (left plate in picture below).

Is MSA selective or differential quizlet?

Explain how mannitol salt agar is selective. Mannitol salt agar contains 7.5% NaCl which makes the medium selective because its concentration is high enough to dehydrate and kill most bacteria.