What is MSB agar?

MSB agar is selective for growth of mutans streptococci and contains per liter: 10.0 g tryptose, 10.0 g peptone, 1.0 g dextrose, 50.0 g sucrose, 4.0 g K2 HPO4, 0.075 g tryptan blue, 0.0008 g crystal violet, 15.0 g agar, 200 units bacitracin and 0.01 g potassium tellurite at a pH of 7.0.