Coagulase Mannitol Agar Base is recommended for the primary isolation and differentiation of pathogenic Staphylococci from clinical specimens and for classifying pure cultures. Due to fermentation of mannitol, the pH of the medium surrounding the coagulase positive colonies drops as indicated by the change in colour of the bromocresol purple indicator, which turns yellow and exhibits yellow zones around the colonies. An opaque area of coagulated plasma forms around the colonies of coagulase positive organisms. Staphylococcus aureus is mannitol positive and coagulase positive while Staphylococcus epidermidis is mannitol and coagulase negative.
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