Mac-Conkey's Agar medium is:

Key Points:- Differential or indicator media depends on the biochemical properties of a microorganism growing in the presence of specific nutrients or indicators, such as neutral red, phenol red, eosin, or methylene blue. The medium changes color when a bacterium grows in them. For example, S. typhi grows as black colonies on Wilson and Blair medium containing sulfite. Lactose fermenting bacteria, such as E. coli produce pink colonies, whereas non-lactose fermenting bacteria, such as Salmonella spp. form pale or colorless colonies on MacConkey agar. Fermentation of lactose in the medium makes it acidic and leads to the formation of pink colonies in the presence of neutral red. Parija SC. Textbook of Microbiology & Immunology. Elsevier Health Sciences; 2014. Page: 36