Sorbitol MacConkey Agar is a specialized medium designed for the selective isolation and identification of enterohemorrhagic Escherichia coli O157:H7. It employs a sorbitol fermentation identification mechanism to achieve precise differentiation: E. coli O157:H7 does not ferment sorbitol, producing colorless or grayish-white colonies often with a grayish-brown center; In contrast, non-sorbose-fermenting strains such as common Escherichia coli and Salmonella produce acid, turning the medium red and forming pink or peach-colored colonies.