Side One: Columbia Agar & Horse Blood - A general purpose medium enriched with 5% Defibrinated Horse Blood, suitable for the isolation of most organisms, including many fastidious anaerobes. Side Two: Bacitracin Chocolate Agar - A highly nutritious medium enriched with Horse Blood, where the blood has been ‘chocolated’ by heating the medium to 60°C. The addition of the selective agent, Bacitracin, makes this medium particularly suitable for the selective isolation of Haemophilus spp.