Brain heart infusion agar is very nutritious general-purpose medium and is suitable for the isolation of most micro-organisms including many fastidious organisms.
The formulation is a modification of that from Rosenow and Hayden.
The medium is not recommended for the determination of haemolytic reactions because of the glucose content.
The nitrogen, vitamin and carbon sources are supplied by the Brain-Heart infusion solids and peptone.
Glucose serves as the carbohydrate source and sodium chloride aids in maintaining the osmotic balance.
A phosphate buffer, disodium hydrogen phosphate, is incorporated to help neutralize any acids produced as a result of glucose utilization and thus maintain viability of the organisms.
NB: Organisms that produce large amounts of acid in the medium may overwhelm the buffering system and as a result may ‘auto-sterilize’ the culture.