MANNITOL SALT AGAR PLATE

Mannitol Salt Agar Plate makes identification easier by combining selective inhibition with a simple colour-based differentiation. The concentration of salt is high (7.5% sodium chloride), which prevents growth of most bacteria but permits growth of salt-tolerant Staphylococcus species. This makes the medium especially useful for the recovery of pathogenic staphylococci from mixed clinical and environmental samples.
What sets this medium apart is its ability to separate organisms depending on the mannitol fermentation. Staphylococcus aureus ferments mannitol and the production of acid by mannitol fermentation causes phenol red indicator to change from red to yellow resulting in the production of yellow colonies with yellow zones. In contrast, most species of coagulase-negative Staphylococcus do not ferment mannitol and therefore produce red or pink colonies without changing the surrounding medium. However, some organisms like Staphylococcus saprophyticus, can ferment mannitol and need to be identified by further biochemical tests.
The composition contains peptic digest of animal tissue, pancreatic digest of casein, beef extract as a source of essential nutrients and mannitol as a carbohydrate to be fermented. Mannitol Salt Agar Plate is widely used in clinical diagnostics, food microbiology, pharmaceutical quality control, and research laboratories for the selective isolation and preliminary differentiation of Staphylococcus species.

A selective and differential medium for isolating Staphylococcus species and distinguishing mannitol-fermenting Staphylococcus aureus from other staphylococci.