Blood agar can be used for isolation and cultivation of fastidious and non-fastidious bacteria. The blood agar plates are incubated at different temperatures and in different atmospheres depending on the actual bacterium.
The medium contains:
Bacteria can also be differentiated, based on their capacity to secrete hemolysins, by cultivation on blood agar. Hemolysins are substances (usually enzymes or porins), which have the capacity to lyse red blood cells. The hemolysis will cause a clearing zone of the blood agar around the colonies. Bacteria can cause different types of hemolysis:
Note that the α-hemolysin of staphylococci causes complete hemolysis, whereas their β-hemolysin causes incomplete hemolysis.