Used for the selective isolation of Salmonella and Shigella species from clinical, food, and water samples. It inhibits Gram-positive bacteria and most non-Salmonella, non-Shigella Gram-negative organisms, allowing target pathogens to grow as distinct colonies. Salmonella typically forms colorless or black colonies due to hydrogen sulfide production, while Shigella appears as colorless, non-H2S-producing colonies. Commonly used in diagnostic laboratories and food safety testing to detect enteric pathogens responsible for gastroenteritis and foodborne outbreaks.