IBI’s Todd-Hewitt Broth is intended for the cultivation and serological typing of Group A hemolytic streptococci. Todd-Hewitt broth is formulated according to Updyke and Nickels modification of the medium originally described by Todd-Hewitt.
Studies comparing various commercial broth formulas, dehydrated Todd-Hewitt broth and broth prepare from fresh infusion of beef heart, showed that the dehydrated Todd-Hewitt Broth performed equally well to the fresh infusion and superior to other commercially prepared products.
Todd-Hewitt broth is composed of beef heart infusion, yeast extract, and casein, which are excellent nutritional components. The formation of protease is prevented which allows the production of type specific M protein. Dextrose is a source of carbon and energy and is fermented by the streptococci. The acid by-products of the fermentation are neutralized by the presence of sodium carbonate and sodium phosphate.