SUMMARY
Muller first described the use of Tetrathionate Broth for the cultivation of Salmonella spp. (1) He found the medium to be inhibitory to lactose-fermenting Enterobacteriaceae while allowing unrestricted growth of Salmonellae. Schaeffer later demonstrated the medium to posses enrichment properties for Salmonellae. (2) In addition, formula modifications were made by Kauffman who reported enhanced recovery of Salmonella spp. while suppressing the growth of undesirable microorganisms. (3,4) However, Proteus and some other species of accompanying flora are not inhibited by this medium alone and are able to reduce tetrathionate. Consequently, using more than one selective agent in the media promotes the isolation of Salmonella from samples containing multiple serotypes. (5)
Tetrathionate Broth with Brilliant Green contains bile salts which are inhibitory to gram-positive and gram-negative microorganisms other than Salmonella spp. Iodine-Iodide Solution (Cat. no. Z129) is added to the prepared medium just prior to inoculation. The use of Iodine-Iodide Solution promotes the production of tetrathionate which inhibits the growth of coliforms and other enteric bacteria. (6,7) Calcium carbonate buffers the production of sulfuric acid generated during the reduction of tetrathionate. Sodium thiosulfate provides a source of sulfur. Finally, the addition of brilliant green to the medium aids in the suppression of predominantly gram-positive bacteria.