TPEY Agar Base is recommended for selective isolation and enumeration of Staphylococci from food. Staphylococcus aureus produce black coloured colony with clear zone or halo around the colony due to lecithinase activity. The coagulase-positive staphylococci are differentiated by their formation of black or dark grey colonies with a zone of precipitated egg yolk around the colonies or a clear zone around the colonies and precipitation below the colonies. Coagulase-negative organisms may produce small black pin point colonies without egg yolk precipitation or clearing around the colonies.