(AB) Todd Hewitt Broth 500G

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-Hewift Broth, and broth prepared from fresh infusion of beef heart showed that the dehydrated Todd-Hewitt Broth performed equally to the fresh infusion and superior to the other commercially prepared products. Todd-Hewift Broth was utilized by Moody et al. in fluorescent procedures for identifying Group A streptococci in throat cultures. Todd-Hewift Broth is composed of beef heart infusion, yeast extract and casein which are excellent nutritional components. The formation of proteinase is prevented allowing the production of type specific M protein. Dextrose is a source of carbon and energy and is fermented by the streptococci. The acid byproducts of the fermentation are neutralized by the presence of sodium carbonate and sodium phosphate. Broth medium intended for the cultivation and serological typing of group A hemolytic streptococci. (Alpha Biosciences # T20-106-500gm)

Use: Broth medium intended for the cultivation and serological typing of group A hemolytic streptococci.

Description: 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-Hewift Broth, and broth prepared from fresh infusion of beef heart showed that the dehydrated Todd-Hewitt Broth performed equally to the fresh infusion and superior to the other commercially prepared products. Todd-Hewift Broth was utilized by Moody et al. in fluorescent procedures for identifying Group A streptococci in throat cultures. Todd-Hewift Broth is composed of beef heart infusion, yeast extract and casein which are excellent nutritional components. The formation of proteinase is prevented allowing the production of type specific M protein. Dextrose is a source of carbon and energy and is fermented by the streptococci. The acid byproducts of the fermentation are neutralized by the presence of sodium carbonate and sodium phosphate.

Formula* per Liter:

• Beef Heart Infusion .......................... 3.1g
• Yeast Enriched Peptone ............ 20.0g
• Dextrose ........................................... 2.0g
• Sodium Chloride ........................... 2.0g
• Disodium Phosphate ....................... 0.4g
• Sodium Carbonate ....................... 2.5g

Final pH: 7.8 ± 0.2 at 25.0°C

* Grams per liter may be adj. or formula supplemented to obtain desired performance

Preparation: Mix 30 grams of the medium in one Liter of purified water until evenly dispersed. Heat with repeated stirring to dissolve completely Distribute and autoclave at 121.0°C for 15 minutes.

Quality Control Specifications:

1. The powder is homogeneous, free flowing and light beige.
2. Visually the prepared medium is clear and gold to amber.
3. Expected cultural response after 18-24 hours at 35.0°C.

Organism                                                                        Result

Enterococcus faecalis ATCC 29212                                Growth

Streptococcus pneumonia ATCC 6305                            Growth

Streptococcus pyogenes ATCC 19615                             Growth

Storage: Store the sealed bottle containing the dehydrated medium at 2 to 30.0°C. Once opened and recapped, place the container in a low humidity environment at the same storage temperature. Protect it from moisture and light. The dehydrated medium should be discarded if it is not free flowing or if the color has changed from the original light beige color.