Novobiocin-tetrathionate broth: a medium of improved selectivity for the isolation of Salmonellae from faeces.

The selective cultivation of bacteria by incorporating chemicals in the media depends on supplying a substance which either stimulates the growth of the species to be isolated or inhibits unwanted species. Tetrathionate is a good selector of Salmonellae in faeces culture, and is believed to act in both ways. Tetrathionate reducers, such as Salmonellae, flourish in broth containing it, whereas a high concentration of tetrathionate inhibits many other faecal organisms (Knox, Gell, and Pollock, 1943). Unfortunately, however, members of the Proteus group are powerful tetrathionate reducers, and when they