MacConkey Agar, RS 500G

MacConkey Agar, RS is recommended For isolating and differentiating Gram negative enteric bacilli from specimens containing swarming strains of Proteus species. Lactose is a fermentable carbohydrate, bile salts and crystal violet are selective agents that inhibit growth of gram-positive organisms. Neutral red is the pH indicator dye. Lactose fermenting strains such as Escherichis coli grow as red or pink colonies and may be surrounded by a zone of acid precipitated bile. Lactose non-fermenting strains, such as Shigella and Salmonella are colourless, transparent and typically do not alter appearance of the medium.