Mannitol Salt Agar is both selective and diffferential
Selective:
Mannitol salt have very high level salt content hence it only allow the growth of Staphylococci as most other bacteria are unable to withstand the high salt condition for growth.It allows the growth of Gram positive bacteria and inhibits the growth of Gram negative bacteria.
Differential:
MSA contains mannitol and indicator phenol red.
*Coagulase-positive Staphylococci will produce yellow colonies with yellow zone
*Coagulase-negative Staphylococci will produce small pink or red colonies with no colour change to the medium
