Baird Parker Agar is a selective medium for Staphylococcus aureus (S. aureus) in food and other samples, as it allows good differentiation of coagulase-positive strains. This medium is also known as Staphylococcus Selective Agar. It is a synthetic medium. Sodium pyruvate has been added as a selective growth stimulant, and egg yolk emulsion as a differentiating agent. Tryptone, HM B peptone and yeast extract are sources of nitrogen, carbon, sulfur and vitamins. Sodium pyruvate not only protects damaged cells and aids recovery, but also stimulates the growth of Staphylococcus aureus without destroying selectivity. A strong correlation was found between the coagulase test and the presence of a clear area of lipolysis in this medium, which is due to the lecithinase of the decomposing Staphylococci, the egg yolk. Almost 100% of coagulase-positive staphylococci are capable of reducing tellurite, which produces black colonies, while other staphylococci may not.