hromogenic media utilize synthetic chromogenic enzyme substrates in order tospecifically target pathogenic species (or groups of species) based on their enzymeactivity. Such enzyme activity is never completely species specific, necessitating the useof complementary enzyme substrates and/or selective agents. The majority of chro-mogenic media are therefore both selective and differential, accommodating theinhibition of nontarget organisms (e.g., using antibiotics or other inhibitors) andenabling target pathogens to grow as colored colonies due to their metabolism (usuallyby hydrolysis) of one or more chromogenic enzyme substrates.