Mannitol salt Agar

Mannitol Salt Agar (MSA) (Chapman Medium) is a selective and differential medium formulated according to Chapman’s recommendations for the isolation of presumptive pathogenic Staphylococcus species, particularly Staphylococcus aureus.

The high concentration of sodium chloride in the medium inhibits most other bacteria, making it highly selective for staphylococci. The medium contains pancreatic digest of casein, peptic digest of animal tissue, and beef extract, which provide essential nutrients such as nitrogen, vitamins, minerals, and amino acids required for bacterial growth.