For the selective enrichment of salmonellae from various materials.

This broth complies with the specifications given in the United States Pharmacopeia XXVI (2003) and the recommendations of the APHA (1992).

Mode of Action
Tetrathionate and excess thiosulfate (PALUMBO and ALFORD 1970) suppress coliform microorganisms and other accompanying bacteria, whereas all tetrathionate-reducing bacteria (e.g. salmonellae and Proteus) can multiply more or less normally in this medium. Acidic tetrathionate decomposition products are formed, which are neutralized by calcium carbonate Bile salts largely inhibit all microorganisms, which do not normally live in the intestine. The United States Pharmacopeia recommends the addition of brilliant green, which suppresses,
above all, the Gram-positive microbial flora. The resulting culture medium has a very strong inhibitory effect; it is therefore sometimes better to omit the brilliant green in order to obtain satisfactory yields of salmonellae. According to JEFFRIES (1959), Proteus can be suppressed by adding 0.04 g novobiocin/litre.

Typical Composition (g/litre)
Peptone from casein 2.5;
Peptone from meat 2.5;
Bile salt mixture 1.0;
Calcium carbonate 10.0;
Sodium thiosulfate 30.0.

Also to be added: Potassium iodide 5.0; iodine 6.0; if required brilliant green 0.01.

Preparation
Suspend 46 g/litre, heat briefly to the boil and cool rapidly.
Do not autoclave.

Prior to use, add 20 ml iodine/potassium iodide solution/litre, if desired 10 ml of a 0.1 % brilliant green
solution/litre and if required 0.04 g novobiocin/litre. Avoid any further heating.
When dispensing the prepared medium, make sure that any precipitate formed is evenly suspended.

Preparation of the iodine/potassium iodide solution: Iodine 6 g; potassium iodide 5 g; distilled water 20 ml.
The ready-to-use broth should be prepared and used the same day.
The medium is turbid and green with white sediment (calcium carbonate).