Baird Parker Agar is used for the cultivation of Staphylococcus aureus from foodstuffs according to ISO 6888, and is not intended for use in the diagnosis of disease or other conditions in humans.
Originally introduced in 1962, this medium was developed by Baird-Parker to overcome the problems of recovering damaged Staphylococcus aureus from foodstuffs. This version of the medium is formulated according to ISO 6888-1:1999 A1:2003 and is in compliance with ISO 6888-2:2003 A1:2003 and ISO 6888-3:2003.
Baird-Parker medium is highly selective by nature, due to the presence of potassium tellurite and lithium chloride. Tellurite inhibits most coliforms and is also reduced to telluride by S. aureus, giving the typical black colonies. Glycine and sodium pyruvate are both used as growth factors by staphylococci while the pyruvate also neutralizes any toxic peroxides that may be formed.
When Baird-Parker medium is used with Egg Yolk Tellurite (NCM4010), presumptive S. aureus appear as black colonies demonstrating lecithinase activity (an opaque zone around the colony) and lipase activity (a zone of clearing encircling the opaque zone). Suspected S. aureus colonies should be confirmed with RPF for coagulase or latex agglutination test.
Rabbit plasma fibrinogen (NCM4052) is a more specific alternative to egg yolk tellurite and allows the direct detection of coagulase-positive S. aureus. Typical S. aureus appear as black colonies surrounded by a zone of precipitation (demonstrating coagulase activity). This is recognized as the gold standard method for the identification of S. aureus. RPF overcomes any issues with atypical colony forms and its use means further confirmatory tests are not necessary.
