A medium recommended by the Harmonised European Pharmacopoeia for isolation and identification of bile-tolerant Gram-negative bacteria from non-sterile pharmaceutical products.
Conforms to USP/EP/JP performance specification. Yeast extract provides vitamins and gelatin serves as source of carbon and nitrogen. Glucose is a fermentable carbohydrate and sodium chloride maintains the osmotic balance. Bile salts and crystal violet act as selective agents inhibiting many Gram-positive bacteria. The formulation is a modification of Violet Red Bile Agar by Mossel which substitutes lactose for glucose. Enterobacteriaceae, such as Escherichia coli and Salmonella spp., are able to ferment glucose. This produces acid which results in a pH drop indicated by neutral red resulting in pink colonies. Enough acid production will cause the precipitation of bile salts resulting in a bile precipitate or halo around glucose fermenting bacteria. Non-glucose fermenting bile tolerant bacteria such as Psuedomonas aeruginosa grow but remain colourless with no bile precipitate. According to the Harmonised European Pharmacopoeia, Enterobacteria Enrichment Broth-Mossel is used as a selective enrichment broth, with subculture performed onto Violet Red Bile Glucose Agar (VRBGA).