Listeria Selective Broth Base is recommended for selective isolation and cultivation of Listeria monocytogenes from clinical specimens. This medium is formulated as per Lovett et al for the selective enrichment of Listeria species from milk and milk products and other foods. Nalidixic acid inhibits growth of gram-negative organisms and acriflavin suppresses gram-positive microorganisms. Acriflavin is an acridinic derivative with bacteriostatic properties towards many gram-positive bacteria and a weak fungicidal activity.