Mannitol Salt Agar

Mannitol Salt Agar (MSA) is a specialized growth medium used in laboratories to identify certain bacteria, mainly Staphylococcus species. It contains a high amount of salt, which inhibits non-staphylococcal bacteria, and a sugar called mannitol. If the bacteria can ferment mannitol, they produce acid, causing the medium's color to change from red to yellow. This change helps scientists determine if the bacteria are pathogenic staphylococci, such as Staphylococcus aureus. Overall, MSA is a useful tool for selectively growing and identifying staph bacteria based on their ability to tolerate salt and ferment mannitol.