SS Agar is a differential and selective medium used for the isolation of Salmonella and some Shigella species from pathological specimens and suspected foods. It contains bile salts, brilliant green, and sodium citrate, which inhibit the growth of most gram-positive and coliform bacteria. Lactose is also added to the medium, which allows for the differentiation of lactose-fermenting and non-lactose-fermenting organisms. It is widely employed in clinical and food testing laboratories to identify these potentially harmful pathogens, aiding in the diagnosis and monitoring of infections caused by these bacteria. The agar's formulation provides specific nutrients and chemicals that allow Salmonella and Shigella colonies to grow and exhibit characteristic appearances, simplifying their identification.