Modified Vogel and Johnson Agar for Staphylococcus aureus.

The formula for a modified Vogel and Johnson Agar is presented. In addition to the ingredients found in Vogel and Johnson Agar, the new medium contains, per liter: 5 g of beef extract, 2 g of deoxyribonucleic acid, 2 g of phosphatidyl choline and 780 units of catalase spread on the plates before inoculation. This new medium is as effective as Baird-Parker Agar in enumeration of stressed Staphylococcus aureus , and in enumeration of staphylococci from naturally contaminated processed food samples.