Blood Agar Base is used for the isolation, cultivation, and detection of haemolytic reaction of fastidious microorganisms. It is suitable for isolating and cultivating a wide range of microorganisms with difficult growth characteristics. Upon adding blood, it can be utilized for determining haemolytic reactions. The heart infusion and meat peptone are rich sources of nitrogen, vitamins, minerals, and amino acids essential for growth. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Bacteriological agar is the solidifying agent. The addition of blood provides extra growth factors for fastidious microorganisms. This is the basis for determining haemolytic reactions. Haemolytic patterns may vary with the type of blood or base medium used. For example, defibrinated sheep blood gives best results for Group A streptococci.