Fluid Thioglycolate Medium is used for sterility testing. This medium conforms to Harmonized USP/EP/JP requirements and is not intended for use in the diagnosis of disease or other conditions in humans.

Fluid Thioglycolate Medium is recommended by the Harmonized Pharmacopoeia for sterility testing and conforms to USP/EP/JP performance specification. In this formulation casein and yeast extract provide a source of nitrogen, essential vitamins and amino acids. The glucose provides a carbon source and sodium chloride maintains osmotic balance. L-Cystine and sodium Thioglycolate act as reducing agents to create an anaerobic environment and maintain a low Eh. This is aided by the low level of agar which reduces the oxygen permeability through the medium. Resazurin is an oxidation indicator which turns from colorless to red/pink when oxidised. Sodium Thioglycolate also serves to inactivate mercurial compounds. If after sterilization more than the upper one third of the medium has become red/pink it may be restored once by heating in a water bath or in free-flowing steam until the color disappears. Ensure the media is cooled quickly and prevent the introduction of non-sterile air into the containers.