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Material Safety Data Sheet

Organisms

Organisms in the Clinical sector this product works with:

Dehydrated Culture Media

Sector: Clinical

TODD-HEWITT BROTH

Code: CM0189

A medium for the production of antigenic streptococcal haemolysin and the cultivation of streptococci prior to serological grouping.

Typical Formula*

gm/litre

Infusion from 450 g fat-free minced meat

10.0

Tryptone

20.0

Glucose

2.0

Sodium bicarbonate

2.0

Sodium chloride

2.0

Disodium phosphate

0.4

pH 7.8 ± 0.2 @ 25°C

* Adjusted as required to meet performance standards

Directions
Dissolve 36.4 g in 1 litre of distilled water. Mix well, distribute into containers and sterilise by autoclaving at 115°C for 10 minutes.

Description
An easily reconstituted, dehydrated modification of the medium originally described by Todd and Hewitt1 for the production of antigenic streptococcal haemolysin. Fermentation of glucose, which is included as a growth stimulant, would lead to the destruction of haemolysin by the acid produced; consequently, the medium is buffered with sodium bicarbonate and sodium phosphate.

It has been found that inorganic phosphates have a stimulating effect on the growth of pneumococci quite apart from their buffering power.
Todd-Hewitt Broth may be employed as an alternative to serum broth or horse-flesh digest broth, for the cultivation of streptococci prior to serological grouping2.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared medium at 2-8°C.

Appearance
Dehydrated medium: Straw coloured, free-flowing powder
Prepared medium: Straw coloured solution       

Quality control

Positive controls:

Expected results

Streptococcus pyogenes ATCC® 19615*

Turbid growth.

Streptococcus pneumoniae ATCC® 6303*Turbid growth.

Negative control:

 

Uninoculated medium

No change.

* This organism is available as a Culti-Loop®

Precautions
Streptococcus species grown in Todd-Hewitt Broth and harvested as antigens to raise antibodies, will sometimes carry antigenic material from the broth. This problem must be looked for in the antisera. If detected it would be preferable to use another medium to grow the test streptococci.

References
1. Todd E. W. and Hewitt L. F. (1932) J. Path. Bact. 35(1). 973-974.
2. Finegold S. M. and Martin W. J. (1982) Diagnostic Microbiology. C. V. Mosby Co. St. Louis. USA. p. 645.

 
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