Columbia CNA Agar Base (Dehydrated)

Selectively isolate gram-positive cocci using Thermo Scientific™ Remel™ Columbia CNA Agar Base (Dehydrated). Columbia Agar Base was first described by Ellner, Stoessel, Drakeford, and Vasi in 1966 as an improved agar base¹ which was capable of growing fastidious and nonfastidious organisms from clinical specimens. Ellner et al. incorporated colistin and nalidixic acid in the base to produce a selective medium for isolating gram-positive organisms (e.g., streptococci, staphylococci) from specimens containing mixed flora.

Carry out primary selective isolation of gram-positive cocci using Columbia CNA Agar Base.

• Selective: Nalidixic acid and colistin inhibit most gram-negative bacilli.
• Ease of Identification: Use of sheep blood enables the demonstration of hemolytic activity.

This medium contains peptones which supply growth factors such as nitrogen, carbon, vitamins, and trace elements essential for bacterial growth. Beef extract and corn starch serve as sources of energy and yeast extract supplies B-complex vitamins. Colistin and nalidixic acid inhibit most gram-negative bacilli. Sheep blood provides the X factor (hemin) necessary for the growth of many bacteria and enables demonstration of hemolytic activity.

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