TODD HEWITT BROTH
|Cat. no. K79||Todd Hewitt Broth, 15x103mm Tube, 5ml||20 or 100 tubes/box|
|Cat. no. K112||Todd Hewitt Broth, 15x103mm Tube, 1ml||20 or 100 tubes/box|
|Cat. no. R33||Todd Hewitt Broth with Tween®, 13x100mm Tube, 0.5ml||20 or 100 tubes/box|
Hardy Diagnostics 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.
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)
Hardy Diagnostics 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. The addition of Tween®80 minimizes the surface tension that develops when using plastic seed trays and pipette tips for microdilution antimicrobial susceptibility testing.
Ingredients per liter of deionized water:*
|Pancreatic Digest of Casein||10.0gm|
|Beef Heart Infusion||3.1gm|
Additionally, Todd-Hewitt Broth with Tween® contains:
Final pH 7.8 +/- 0.3 at 25ºC.
* Adjusted and/or supplemented as required to meet performance criteria.
STORAGE AND SHELF LIFE
Storage: Upon receipt, store at 2-30ºC. away from direct light. Todd Hewitt Broth (Cat. no. K112) and Todd Hewitt Broth with Tween® (Cat. no. R33) should be stored at 2-8ºC. away from direct light. Media should not be used if there are any signs of deterioration, discoloration, contamination, or if the expiration date has passed. Product is light and temperature sensitive; protect from light, excessive heat, moisture, and freezing.
Specimen Collection: Specimens should be submitted directly to the laboratory without delay and protected from excessive heat and cold. If there is to be a delay in processing, specimens should be inoculated into an appropriate transport media and refrigerated until inoculation.
Method of Use:
1. Allow the medium to warm to room temperature prior to use.
2. Inoculate the tube directly with the specimen swab.
3. Express excess fluid from the swab while removing from the medium.
4. Incubate the inoculated broth (caps loose) at 35-37ºC. in 5-10% CO2 for 2-5 hours prior to use in fluorescent antibody procedures or incubate for 24 hours if extraction procedures for serological typing are to be performed.
5. Follow serological and extraction procedures as directed by the manufacturer.
INTERPRETATION OF RESULTS
Adhere to standards presented by the manufacturer of the test chosen.
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 non-selective. 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 loops, other culture media, swabs, applicator sticks, incinerators, and incubators, etc., as well as serological and biochemical reagents, are not provided.
MATERIALS REQUIRED BUT NOT PROVIDED
|Test Organisms||Inoculation Method*||Incubation||Results|
ATCC ® 19615
ATCC ® 12386
User Quality Control
Todd Hewitt Broth should appear clear, and medium amber in color.
1. Elliott, S.D. 1945. J. Exp. Med.; 81573.
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.
Tween is a registered trademark of ICI Americas, Inc.