For selective isolation of Salmonellae other than Salmonella typhi from faeces and foods etc.
BRILLIANT GREEN AGAR BASE, MODIFIED is used for the selective isolation of Salmonellae other than Salmonella typhi from faeces and foods etc. Salmonellae and other than S. typhi from feces and other materials. Brilliant Green Agar Base, Modified, as a primary plating medium for isolation of Salmonella species was first described by Kristensen et. al. and further modified by Kauffmann.The medium contains Proteose peptone and Yeast extract as sources of carbon, nitrogen, vitamins, amino acids and essential nutrients. The two sugars namely Lactose and Sucrose serve as energy sources. Fermentation of Lactose and Sucrose in the medium results in the formation of acidic pH which is detected by Phenol red indicator. Brilliant green dye inhibits gram-positive bacteria and a majority of gram-negative bacilli. Phenol red serves as a pH indicator and yields a yellow color as a result of acid production on fermentation of the Lactose and Sucrose in the medium. Sodium chloride maintains the osmotic equilibrium. Agar is a solidifying agent. Clinical specimens can be directly plated on this medium. However, being highly selective, it is recommended that this medium should be used along with a less inhibitory medium to increase the chances of recovery. The medium can further supplemented with sulpha supplements to inhibit contaminating microorganisms when the sample is suspected to contain large number of competing organisms along with Salmonella species. Non-lactose fermenting bacteria develop white to pinkish red colonies within 18 - 24 hours of incubation. Salmonella Typhi and Shigella species may not grow on this medium. Moreover Proteus, Pseudomonas and Citrobacter species may mimic enteric pathogens by producing small red colonies.