A very nutritious isotonic general purpose medium with a low concentration of Glucose to stimulate early growth, Brain Heart Infusion Broth is suitable for the isolation of most micro-organisms including many fastidious organisms and, with enrichment as appropriate, is suitable as a base for blood culture medium. A phosphate buffer is incorporated to help neutralise any acids produced as a result of Glucose utilisation 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 ‘auto-sterilise’ the culture.