Developed by Donnelly and Baigent, UVM Modified Listeria Enrichment Broth medium is used for the selective isolation and enrichment ofListeriaspp. from clinical specimens and food. Within the formula, the high tolerance to Sodium Chloride ofListeriais 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 byListeriaspp. 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.