Blood agar supports the growth of most fastidious organisms and allows for the observation of hemolytic reactions. Hemolysis is classified into three types: 1. Alpha hemolysis: Partial hemolysis causing a greenish discoloration around the colonies. 2. Beta hemolysis: Complete hemolysis resulting in a clear zone surrounding the colonies. 3. Gamma hemolysis: No hemolysis, with no change in the medium around the colonies.
These reactions help in differentiating species such as Streptococcus pneumoniae (alpha-hemolytic) and Streptococcus pyogenes (beta-hemolytic), which are significant in epidemiological studies of respiratory and systemic infections.
