Brain Heat Infusion Broth is highly nutritious and is recommended for the propagation of pathogenic cocci and other fastidious organisms associated with blood culture work and allied pathological investigations, as well as for Staphylococcus aureus enrichment.
Principle of Brain Heat Infusion Broth
Rosenow devised the original BHI by adding brain tissue to dextrose broth. Brain Heart Infusion Broth is a highly nutritious medium and is also well buffered to support the growth of wide variety of microorganisms. The ISO committee recently recommended this medium for the detection of Staphylococcus aureus. With the addition of desired additives, this medium can be used to cultivate a variety of bacteria. With the addition of 6.5 percent sodium chloride, it becomes selective for the isolation of various salt-tolerant bacteria such as Enterococci. BHI is also used to prepare inocula for antimicrobial susceptibility tests.
Composition of Brain Heat Infusion Broth
| Ingredients | Gms / Litre |
|---|---|
| Peptic digest of animal tissue | 10.000 |
| Calf brain, infusion (solids) | 12.500 |
| Beef heart, infusion (solids) | 5.000 |
| Dextrose | 2.000 |
| Sodium chloride | 5.000 |
| Disodium phosphate | 2.500 |
| Final pH ( at 25°C) | 7.4±0.2 |
Preparation procedure of Brain Heat Infusion Broth
- Dissolve 37 grams in 1000 mL of distilled water.
- Dispense into bottles or tubes and sterilize for 15 minutes in an autoclave at 15 lbs pressure (121°C).
- The medium should be used the same day it is prepared for the best results; otherwise, it should be boiled or steamed for a few minutes and then cooled before use.
Quality Control of Brain Heat Infusion Broth
| Appearance | Cream to yellow homogeneous free flowing powder |
| Color and Clarity of prepared medium | Light amber coloured, clear to slightly opalescent solution |
| Reaction | Reaction of 3.7% w/v aqueous solution at 25°C. pH : 7.4±0.2 |
| pH | 7.20-7.60 |
| Cultural Response | Cultural characteristics observed after an incubation at 35-37°C for 18-24 hours. |
Cultural Response on Brain Heat Infusion Broth
| Organism | Inoculum (CFU) | Growth |
|---|---|---|
| Neisseria meningitidis | 50-100 | luxuriant |
| Staphylococcus aureus | 50-100 | luxuriant |
| Streptococcus pyogenes | 50-100 | luxuriant |
| Streptococcus pneumoniae | 50-100 | luxuriant |
Storage and Shelf Life
Store below 30°C in tightly closed container and the prepared medium between 2 – 8°C. Use before expiry date on the label.
Reference
- Rosenow, 1919, J. Dental Res., 1:205.
- Roseburg T. et al, 1944, J. Inf. Dis., 74:131.
- Conant N.F., 1950, Diagnostic Procedures and Reagents, 3rd Ed., APHA, Inc., New York, p. 452.
- MacFaddin J.F., 1985, Media for Isolation-Cultivation-Identification-Maintenance of Medical Bacteria, Vol. I, Williams and Wilkins, Baltimore.
- International Organization for Standardization (ISO), 1983, Enumeration of Staphylococcus aureus, Draft ISO/DIS 6880.
