Violet Red Bile Glucose Agar (VRBGA) is used to detect and enumerate Enterobacteriaceae in food and dairy products. The Enterobacteriaceae group includes lactose-fermenting coliforms, lactose-fermenting strains of E. coli and lactose-fermenting species such as Salmonella and Shigella. When examining certain foods, it is desirable to detect Enterobacteriaceae rather than coliform bacteria. Red Violet Bile and Glucose Agar contains a pancreatic digestate of gelatin as a source of carbon, nitrogen, vitamins and minerals. The yeast extract provides B-complex vitamins that stimulate bacterial growth. Glucose is a carbohydrate. Bile salts and crystal violet inhibit gram-positive bacteria. Microorganisms capable of fermenting glucose produce red colonies with red-violet halos (bile precipitation) in the presence of neutral red, a pH indicator. Sodium chloride maintains osmotic balance. Agar is the solidifying agent.