Tellurite Glycine Agar Base is recommended for quantitative detection of coagulase positive Staphylococci from food and other sources like skin, mucous membranes, faeces, soil and air. Lithium chloride and potassium tellurite are the inhibitors of the coagulase negative staphylococci and a wide variety of other bacteria. Potassium tellurite also serves as a differential agent since coagulase-positive staphylococci reduce tellurite and form black colonies.