HiCrome™ MacConkey Sorbitol Agar Base

Recommended for the detection of enteropathogenic strains of Escherichia coli O157:H7 that ferments lactose but does not ferment sorbitol and hence produce colourless colonies. Sorbitol fermenting strains of Escherichia coli produce pink-red colonies. The red colour is due to production of acid from sorbitol, absorption of neutral red and a subsequent colour change of the dye when pH of the medium falls below 6.8. Sorbitol positive and beta glucuronidase positive E.coli appears as Blue to purple colour colony. Tellurite-cefixime supplement imparts selectivity.