MacConkey Agar

MacConkey Agar is used for the isolation and differentiation of Gram-negative enteric bacilli in a laboratory setting. Conforms to Harmonized USP/EP/JP Requirements and FDA/BAM. MacConkey Agar is not intended for use in the diagnosis of disease or other conditions in humans. A medium recommended by the Harmonized USP/EP/JP for isolation and identification of Escherichia coli from non-sterile products. Conforms to USP/EP/JP performance specification. Gelatin serves as source of carbon and nitrogen. Lactose 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. Escherichia coli can ferment lactose to produce acid which results in a pH drop. This is 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 lactose fermenting bacteria. Non-lactose fermenting bacteria such as Salmonella spp. grow but remain colorless with no bile precipitate. According to the Harmonized USP/EP/JP, MacConkey Broth is used as a selective enrichment broth, with subculture performed onto MacConkey Agar.