Differential media are bacteriological growth media that contain specific ingredients to allow one to distinguish selected species or categories of bacteria by visual observation. Examples of differential media includes:
Blood agar (used in strep tests) contains bovine heart blood that becomes transparent in the presence of β-hemolytic organisms such as Streptococcus pyogenes and Staphylococcus aureus.
Eosin methylene blue is differential for lactose fermentation.
Streptococcuseosin methylene blue (EMB), which is differential for lactose and sucrose fermentation.
