The toxicity of potassium tellurite to Staphylococcus aureus in rabbit plasma fibrinogen agar

The potassium tellurite concentration, 0.01% w/v, in Baird-Parker agar has been recommended for plasma coagulase media such as pig or rabbit fibrinogen agar. Comparative tests have shown that with some strains of Staphylococcus aureus this level of potassium tellurite is too inhibitory and it should be reduced four-fold to 0.0025% w/v to maximize the isolation rate. It is postulated that egg yolk in Baird-Parker agar has a protective effect on staphylococci against the inhibitory action of tellurite.