Bile esculin agar comes in a slant form. It is 2 tests in one---resistance to 40% bile AND the use of the sugar esculin. Bile is a very inhibitory chemical, particularly at that concentration. IF the ...Bile esculin agar comes in a slant form. It is 2 tests in one---resistance to 40% bile AND the use of the sugar esculin. Bile is a very inhibitory chemical, particularly at that concentration. IF the bacterium grows, the next question is whether it uses the esculin. If your bacterium cannot grow in the presence of bile, the esculin reaction will have to be obtained a different way, using an esculin sugar disc.