MacConkey Agar Base is a solid medium recommended for use in qualitative procedures for the cultivation of gram-negative bacilli.

• Peptones provide nitrogenous nutrients and amino acids
• Sodium chloride maintains osmotic equilibrium
• Crystal violet and bile salts inhibit most gram-positive organisms

MacConkey Agar Base is used with added carbohydrate to differentiate enteric gram-negative bacilli based on fermentation reactions.