Salmonella Chromogenic Medium is a specialized culture medium designed for the selective isolation and direct chromogenic identification of Salmonella. Through a dual mechanism of selective inhibition and enzymatic chromogenic reaction, it causes Salmonella (which does not ferment lactose and expresses specific enzymes) to form characteristic pink, purple, or purplish-red colonies. In contrast, lactose-fermenting bacteria such as Escherichia coli produce blue or blue-green colonies, enabling efficient and intuitive preliminary identification.