Salmonella Shigella Agar is a selective and differential medium that is widely used for sanitary bacteriology to isolate Salmonella and Shigella from faeces, urine, and fresh or canned foods. It has a strong inhibitory power which means a heavy inoculum can be used in the SS agar. It must be streaked in parallel, in a less selective media such as Deoxycholate Agar, MacConkey Agar, Methylene Blue Eosin Agar, XLD Agar, and Enteric Hektoen Agar which increases the probability of detection when the population of microorganisms is scarce. Beef extract and peptone mixture provide nitrogen, vitamins, minerals, and amino acids essential for growth. Lactose is the fermentable carbohydrate providing carbon and energy. Bile salts mixture, sodium citrate and brilliant green inhibit Gram-positive bacteria, most coliform bacteria, and swarming Proteus spp., while allowing Salmonella spp to grow. The neutral red is the pH indicator. Sodium thiosulfate and ferric citrate allow the detection of the H2S producing bacteria. Non-lactose fermenting bacteria produce clear colonies, transparent or colourless, while coliforms like E.coli are sufficiently inhibited, and form small colonies that vary from pink to red in colour. Enterobacter and Klebsiella bacteria will produce larger colonies than E. Coli, mucoid, pale, and opaque cream to pink in colour. Colonies from Proteus and some stains of Salmonella present black centers and a clear halo. This formulation is not recommended for the primary isolation of Shigella.