Bismuth Sulfite Agar
Bismuth Sulfite Agar is used for the isolation of Salmonella spp. A modification by Wilson and Blair, Bismuth Sulfite Agar uses Bismuth and Sodium Sulfite for the selective isolation of typhoid and non-typhoid Salmonella strains. This medium is used particularly for the isolation of Salmonella typhi from clinical and environmental specimens including food, feces, urine, and sewage. Bismuth and Brilliant Green dye act as inhibitors to most enteric bacteria and Gram-positive microorganisms but allow Salmonella typhi to produce black colonies surrounded by a metallic sheen due to the precipitation of iron from Ferrous Sulfate upon reduction to H2S.