HardyCHROM Listeria from Hardy Diagnostics is a chromogenic medium recommended for the selective isolation, differentiation and enumeration of from food by colony color and appearance. HardyCHROM Listeria contains specific chromogenic substrates that result in all species producing turquoise colored colonies when the substrate is hydrolyzed by specific bacterial enzymes. Further, this medium is able to detect the phospholipase activity specific to the two pathogenic species: and, according to the company. These two species will produce turquoise colored colonies surrounded by an opaque white halo within 48 hours, Hardy Diagnostics says.
