General
VRBD (Violet Red Bile Dextrose) Agar is used for selective isolation of Enterobacteriaceae or bile
tolerant gram-negative bacteria from non-sterile pharmaceutical products, foodstuffs and other sample
material.
The formulation of the medium is prepared according to the recommendations of the current ISO 21528. 

Mode of Action
Crystal violet and bile salts inhibit the accompanying bacterial flora. Degradation of glucose is
accompanied by production of acid, which is indicated by a color change to red and by zones of
precipitated bile acids surrounding the colonies. All Enterobacteriaceae are detected as they all degrade
glucose to acid. The culture medium is not, however, absolutely specific for these organisms as some
other accompanying bacteria (e.g. Aeromonas) also show these reactions.