Description
MacConkey Sorbitol Agar is a selective differential medium for detecting Escherichia coli O157:H7.
Bile salts and crystal violet inhibit Gram-positive organisms. Most E. coli ferment sorbitol and form pink-to-red colonies, whereas typical E. coli O157:H7 colonies remain colourless.
Clinical or food material and enrichment cultures are streaked onto the medium and incubated at 35 ± 2°C for 18–24 hours. Colourless presumptive colonies require serological or molecular confirmation.
