Phenylethanol Agar is used with blood for the selective isolation of Staphylococci and Streptococci. Enzymatic Digest of Casein and Soy Peptone are nitrogenous sources. Sodium Chloride maintains the osmotic equilibrium. Phenylethanol is bacteriostatic for Gram-negative bacteria and inhibits DNA synthesis. Agar is the gelifying agent. Addition of Sheep Blood improves bacterial recovery.