THIOGLYCOLLATE USP MEDIUM (ISO 7937) 500 grams/bottle

Thioglycollate Medium is prepared according to the American Pharmacopoeia to perform sterility testing of pharmaceutical products and other devices. This medium is excellent for the cultivation of aerobic and anaerobic microorganisms without the need for an anaerobic jar or paraffin or a special seal. The medium is recommended by the ISO normative 7937 for the enumeration of Clostridium perfringens using the colony count technique in the confirmation step. It is well buffered so that acid or alkaline inocula will hardly alter the reaction of the medium. Thioglycollate Medium is also recommended for the cultivation of Clostridium and Desulfotomaculum nigrificans. Sodium thioglycollate in the medium neutralizes the bacteriostatic effect produced by mercurial compounds used as preservatives in pharmaceutical solutions, making Thioglycollate Media useful in testing material which contain heavy metals. It is necessary to establish the bacteriostatic activity of the product by the method described in the USP (1970) in order to avoid false negative results. The small quantity of agar assists in the detection of contaminants during sterility testing as it delays the dispersion of CO₂, diffusion of O2 and reducing substances. The Nitrogen source is provided by the Enzymatic Digest of Casein and the vitamins by the Yeast extract. Sodium thioglycollate and L-Cystine lower the oxidation-reduction potential of the medium by removing the O2 to maintain a low Eh, therefore preventing the accumulation of peroxides which can be toxic to some organisms. Resazurin is an indicator of oxidation by turning pink. Dextrose is the fermentable carbohydrate providing carbon and energy. Sodium chloride supplies essential electrolytes for transport and osmotic balance. The medium is used in liquid form in test tubes or as a slanted solid with added agar (1.5%).