CRITERION™ TODD HEWITT BROTH

Cat. no. C7090 CRITERION™ Todd Hewitt Broth 60gm
Cat. no. C7091 CRITERION™ Todd Hewitt Broth 500gm
Cat. no. C7092 CRITERION™ Todd Hewitt Broth 2kg
Cat. no. C7093 CRITERION™ Todd Hewitt Broth 10kg
Cat. no. C7094 CRITERION™ Todd Hewitt Broth 50kg

INTENDED USE

Hardy Diagnostics CRITERION™ Todd Hewitt Broth is recommended for the production of antigenic streptococcal hemolysin and the cultivation of streptococci prior to serological grouping. It is also recommended for the cultivation of beta-hemolytic streptococci, pneumococci and other fastidious organisms.

This dehydrated culture medium is a raw material intended to be used in the making of prepared media products, which will require further processing, additional ingredients, or supplements.

SUMMARY

Todd Hewitt Broth was originally developed in 1932 by Todd and Hewitt. Elliot found the medium to be useful in growing group A streptococci for the production of the type specific M protein antigen.(1) Later, the formula was modified by Updyke and Nickel who found the medium to be particularly useful for growing group A streptococci for serological typing.(2)

CRITERION™ Todd Hewitt Broth follows the formula developed by Updyke and Nickel.(2) The medium is composed of beef heart infusion, peptones and yeast extract which all supply necessary growth nutrients. Dextrose is added as an energy source and stimulates streptococcal antigen production. Sodium carbonate and disodium phosphate are included as buffers which serve to protect the hemolysin from inactivation by acid produced from dextrose fermentation.

FORMULA

Gram weight per liter: 30.0gm/L
Pancreatic Digest of Casein 10.0gm
Yeast Extract 10.0gm
Beef Heart Infusion 3.1gm
Sodium Carbonate 2.5gm
Dextrose 2.0gm
Sodium Chloride 2.0gm
Disodium Phosphate 0.4gm

Final pH 7.8 +/- 0.2 at 25ºC.

* Adjusted and/or supplemented as required to meet performance criteria.

STORAGE AND SHELF LIFE

Store the sealed bottle(s) containing dehydrated culture medium at 2-30ºC. Dehydrated culture medium is very hygroscopic. Keep lid tightly sealed. Protect dehydrated culture media from moisture and light. The dehydrated culture media should be discarded if it is not free-flowing or if the color has changed from its original light beige.

Store the prepared culture media at 2-30ºC.

PRECAUTIONS

METHOD OF PREPARATION FOR DEHYDRATED CULTURE MEDIA

1. Suspend 30.0gm of the dehydrated culture media in 1 liter of distilled or deionized water.

2. Heat to boiling and mix to dissolve completely.

3. Sterilize in the autoclave at 121ºC. for 15 minutes.

4. Dispense into sterile tubes.

PROCEDURE AND INTERPRETATION OF RESULTS

For information on procedures and interpretation of results, consult listed references or refer to the prepared media Instructions for Use (IFU) for Cat. No. K79.

LIMITATIONS

Streptococcus spp. grown in Todd Hewitt Broth and harvested as antigen to raise antibodies may carry antigenic material from the broth.

Todd Hewitt Broth is nonselective. Additional tests including subculture to an appropriate agar media, as well as biochemical and/or serological tests, should be performed for complete identification of pure cultures. For more information, consult appropriate references.

MATERIALS REQUIRED BUT NOT PROVIDED

Standard microbiological supplies and equipment such as autoclaves, incinerators, and incubators, etc., are not provided.

QUALITY CONTROL

Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Streptococcus pyogenes
ATCC ® 19615
A 24hr 35°C Aerobic Growth
Streptococcus agalactiae
ATCC ® 12386
A 24hr 35°C Aerobic Growth

User Quality Control

PHYSICAL APPEARANCE

CRITERION™ Todd Hewitt Broth powder should appear homogeneous, free-flowing, and light beige in color. The prepared media should appear clear, and medium amber in color.

REFERENCES

1. Elliott, S.D. 1945. J. Exp. Med.; 81:573.

2. Applied Microbiol.; 2:117, 1954.

3. Isenberg, H.D. Clinical Microbiology Procedures Handbook, Vol. I, II & III. American Society for Microbiology, Washington, D.C.

4. Anderson, N.L., et al. Cumitech 3B; Quality Systems in the Clinical Microbiology Laboratory, Coordinating ed., A.S. Weissfeld. American Society for Microbiology, Washington, D.C.

5. Quality Assurance for Commercially Prepared Microbiological Culture Media, M22. Clinical and Laboratory Standards Institute (CLSI - formerly NCCLS), Wayne, PA.


ATCC is a registered trademark of the American Type Culture Collection.

062716gr