Todd Hewitt Broth (NutriSelect Plus) was originally formulated as a serum-free medium with a high protein and glucose content to support the growth of streptococci for serological studies. The medium is exceptionally rich due to the beef heart infusion and peptic digest of animal tissue, which provide essential nitrogen, amino acids, vitamins, and minerals. Dextrose (glucose) serves as a primary energy source and specifically stimulates the production of hemolysins. Because the fermentation of glucose produces acid, the medium is heavily buffered with sodium phosphate and sodium carbonate to maintain a stable pH (7.8), preventing the inactivation of the sensitive antigenic hemolysins.
Advantages
- Optimized for Fastidious Growth: Specifically designed to support the development and maintenance of type-specific M proteins in Group A streptococci.
- High Nutritional Value: The heart infusion base provides a superior nutrient profile compared to standard meat extract broths.
- Effective Buffering System: Dual-buffer system (phosphate and carbonate) neutralizes acid production, ensuring optimal growth and protecting antigens.
- NutriSelect® Plus Quality: Part of the cost-efficient yet high-quality powdered media line, ensuring consistent performance for routine microbiology.
- Stimulates Hemolysin: Glucose levels are optimized to enhance the production of streptococcal antigens and hemolysins.
Technical specifications
| Catalogue number |
T1438 |
| Brand / Product Line |
Sigma-Aldrich / NutriSelect® Plus |
| Typical Composition (g/L) |
Beef Heart Infusion (from 500g) (10.0); Peptic Digest of Animal Tissue (20.0); Dextrose (2.0); Sodium Chloride (2.0); Disodium Phosphate (0.4); Sodium Carbonate (2.5) |
| pH (at 25 °C) |
7.8 ± 0.2 |
| Appearance |
Yellow colored, homogeneous, free-flowing powder |
| Preparation |
37.0 g/L |
| Storage Temperature |
2 – 25 °C |
Available packaging options
| T1438-100G |
100 g plastic bottle |
| T1438-500G |
500 g plastic bottle |
