The ability to grow in 6.5% NaCl and produce mannitol acid was once considered sufficient to identify S. aureus. Although other Staphylococcus species have these characteristics, mannitol salt agar, as seen here, can still be used for epidemiologic studies in suspected cases of S. aureus outbreaks.
As shown in the image, colonies indicate the ability to grow on 6.5% NaCl, and the yellow pigment indicates acid production from mannitol.
