Used in microbiology for the selective isolation and differentiation of enteric pathogens, particularly Salmonella and Shigella species, from clinical and non-clinical samples. The medium inhibits the growth of Gram-positive bacteria and normal intestinal flora using deoxycholate, allowing selective growth of Gram-negative enteric bacteria. Lactose is included as a fermentable carbohydrate to differentiate lactose fermenters (which produce acid, leading to color changes) from non-fermenters. Hydrogen sulfide production is detected through the formation of black colonies or centers, typically due to iron compounds in the medium reacting with H₂S, aiding in the identification of Salmonella and some E. coli strains. Commonly used in food testing, water analysis, and clinical diagnostics for gastrointestinal infections.