Chocolate agar

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Chocolate agar (CHOC) - is a non-selective, enriched growth medium. It is a variant of the blood agar plate. It contains red blood cells, which have been lysed by heating very slowly to 56 °C. Chocolate agar is used for growing fastidious (fussy) respiratory bacteria, such as Haemophilus influenzae. These bacteria need growth factors, like NAD and hematin, which are inside erythrocytes; thus, a prerequisite to growth is haemolysis of the red blood cells. The agar, which contains no actual chocolate, is named for the coloration only.

In this medium, every bacteria can growth, so culture from faeces is impossible.