Developed by Donnelly and Baigent, UVM Modified Listeria Enrichment Broth medium is used for the selective isolation and enrichment of Listeria spp. from clinical specimens and food. Within the formula, the high tolerance to Sodium Chloride of Listeria is used to inhibit the growth of enterococci, Nalidixic Acid (20 mg/L) to inhibit Gram-negative microorganisms, and Acriflavin to inhibit Gram-positive bacteria. The Esculin is utilized by Listeria spp. and results in the blackening of this medium. Casein Peptone, Beef Extract, Yeast Extract and Peptic Digest of Animal Tissue supply necessary growth nutrients such as amino acids, peptides, vitamins, and electrolytes. The medium is well buffered, containing Disodium and Monopotassium Phosphates, which allows the recovery of pH-sensitive bacteria.