Brain infusion Broth and Agar Principle and composition and growth response

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Brain heart infusion agar MLTGEEKS

Brain heart infusion (BHI) is a nutritious growth medium used to culture a variety of fastidious organisms associated with blood culture work and allied pathological investigations. This nutritious medium has been used to culture pathogenic cocci such as streptococci, pneumococci and meningococci  which are can be challenging to grow on ordinary media.It  is made by combining an infusion from boiled porcine or bovine heart and brain with a variety of other nutrients.

This medium is frequently used both in clinical and research settings and a number of fastidious organisms, including some anaerobic bacteria, yeasts, and other fungi are able to grow well on Brain Heart Infusion. It is  also be used to differentiate between enterococci and lancefield group D streptococci and in the preparation inocula for antimicrobial susceptibility testing

Principle of Brain Heart infusion broth

  • The proteose peptone, HM infusion powder (Calf brain infusion from) and BHI powder (Beef heart, infusion from) serve as sources of nitrogen,carbon, essential growth factors, amino acids and vitamins.
  • Dextrose (Sugar) serves as a source of energy.
  • The disodium phosphate helps in maintaining the buffering action of the medium
  • Disodium chloride will maintain the osmotic equilibrium of the medium.

This media can be modify with the addition of 10% defibrinated sheep blood making it useful for isolation and cultivation of Histoplasma capsulatum and other fungi also for the selective isolation of fungi an addition of  antibiotics like gentamicin and/or chloramphenicol is recommended

Composition of Selenite  Broth

HM infusion powder (Calf brain infusion from) 12.500
BHI powder 5.000
Proteose peptone10.000
Sodium chloride5.000
Dextrose (Glucose)2.000
Disodium phosphate2.500
Final pH at temperature of 25°C7.4±0.2
Also read  Semen Analysis: Sperm Counting Test Procedure and Results

How to Prepare Brain Heart Infusion Broth and Agar

  • Start by suspending 37.0 grams in 1000 ml distilled water.
  • Dispense into bottles or tubes or petri dish and sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes.

Note that for best results, this medium should be used the same day it is prepared, otherwise, it should be boiled or steamed for a few minutes and then cooled before use.

Appearance of BHI after preparation

It has a light to amber coloured, clear solution without any precipitate in tubes and petri dish

Brain infusion biphasic media
Brain infusion biphasic media
Brain infusion agar
Brain infusion agar

Type of Inoculums

  • Food samples
  • Blood
  • Water samples

Cultural response after Incubation

Incubation is done at temperature 35-37°C for 24-48 hours

Streptococcus pneumoniaegood-luxuriant
Neisseria meningitidis good-luxuriant
Streptococcus pyogenesgood-luxuriant
Staphylococcus aureus subsp. aureusgood-luxuriant
Candida albicansgood-luxuriant
Enterococcus faecalis good-luxuriant


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  • Atlas R. M., 1993, Handbook of Microbiological Media, 147-153, CRC Press, Boca Raton, FL. 50-100 50-100 50-100 50-100 50-100 50-100
  • Roseburg T. et al, 1944, J. Inf. Dis., 74:131 6. Conant N. F., 1950, Diagnostic Procedures and Reagents, 3rd Ed., APHA Inc., New York
  • Howard B., Keiser J. F., Weissfeld A. et al, 1994, Clinical and Pathogenic Microbiology, 2nd Ed., Mosby Co.
  • Murray P. R., Baron J. H., Pfaller M. A., Jorgensen J. H. and Yolken R. H., (Eds.), 2003, Manual of Clinical Microbiology, 8th Ed., American Society for Microbiology, Washington, D.C.
Also read  Eosin Methylene Blue (EMB) Agar : Principle purpose and colonies characteristics

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About the Author: Arthur Westmann

DEFFE ARTHUR (AMOEBAMANN) is the founder and author of MLTGEEKS and MLTEXPO.He’s from Cameroon and is currently a Final year State Medical Laboratory Technician (MLT MA). Beyond lab works, he’s a passionate internet user with a keen interest in web design and blogging. Furthermore He likes traveling, hanging around with friends and social networking to do in his spare time.

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