What selective growth media is best suited for isolation of coliform bacteria? How can they be differentiated?

MacConkey's agar. Isolated colonies of coliform bacteria are brick red in color and may be surrounded by a zone of precipitated blue. This type of agar contains neutral-red, crystal violet and bile salts that inhibit gram-positive organisms and allow gram negative organisms to grow. Coliform bacteria are gram negative rods that appear in human feces in great amounts.