Thermo Scientific™ Oxoid™ Todd-Hewitt Broth (Dehydrated), 500G

Thermo Scientific™ Oxoid™ Todd-Hewitt Broth is a specialized culture medium designed to:

1. Prepare antigenic streptococcal hemolysin.
2. Cultivate Streptococci prior to serological groupings, particularly for group A beta-hemolytic Streptococci.
3. Serve as an alternative to serum broth or horse-flesh digest broth.

The medium is well-buffered to neutralize acids produced during glucose fermentation, supporting optimal microbial growth. It conforms to specifications for use in diagnostic and research applications.

Microbial Targets

Todd-Hewitt Broth is specifically designed for:

• Streptococcus species: Facilitates their growth and supports serological grouping by enhancing the production of antigenic factors.
• Other facultatively anaerobic bacteria: Supports growth under aerobic and anaerobic conditions.

Commonly cultivated microorganisms include:

• Streptococcus pyogenes (e.g., group A beta-hemolytic).
• Streptococcus pneumoniae.

Key Features

• Well-Buffered: Sodium phosphate and sodium bicarbonate neutralize acids produced during glucose metabolism.
• Nutrient-Rich: Tryptone provides amino acids and peptides; glucose serves as a carbohydrate source.
• Versatility: An alternative to serum-based media, making it cost-effective and convenient.
• Diagnostic Utility: Recommended for hemolytic and serological studies of Streptococci.
• Ease of Preparation: Supplied as a dehydrated powder that is easily reconstituted.

Typical Formula

Adjustments are made as required to meet performance standards.

Preparation Instructions

1. Dissolve 36.4 g of Todd-Hewitt Broth powder in 1 liter of distilled water.
2. Mix thoroughly to dissolve completely.
3. Sterilize by autoclaving at 121°C for 15 minutes.
4. Cool the medium to room temperature before use.

Applications

1. Production of Streptococcal Hemolysin:
   • Used in antigenic studies of hemolysin production by Streptococci.
2. Cultivation of Beta-Hemolytic Streptococci:
   • Suitable for cultivating Streptococci prior to serological grouping.
3. Alternative to Serum Broth:
   • Functions as a substitute for serum broth or horse-flesh digest broth for cultivating Streptococci.

Storage Conditions and Shelf Life

• Dehydrated Medium: Store at 10–30°C in a dry environment.
• Prepared Medium: Store at 2–8°C away from light.
• Use before the expiry date printed on the label.

Appearance

• Dehydrated Medium: Straw-colored, free-flowing powder.
• Prepared Medium: Clear, straw-colored solution.

Quality Control

QC organisms available as Culti-Loop® products.

Precautions

• Monitor the performance of the broth routinely using standard QC organisms.
• Use as directed for laboratory purposes only.
• Not suitable for diagnostic or therapeutic procedures without proper validation.

References

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