Columbia CNA Agar is used with blood for the selective isolation of Gram-positive cocci in a laboratory setting. Columbia CNA Agar is not intended for use in the diagnosis of disease or other conditions in humans. Ellner et al. described Columbia CNA Agar as a variation of Columbia Blood Agar Base that is selective for gram-positive cocci. Colistin and nalidixic acid are added to the formula, selecting for gram-positive organisms and fungi by suppressing gram-negative bacteria.

• Analyte: gram-positive cocci
• Platform: dehydrated culture media
• Formula: enzymatic digest of casein 5.0g/L, enzymatic digest of animal tissue 8.0g/L, enriched peptone 10.0g/L, starch 1.0g/L, sodium chloride 5.0g/L, colistin 0.015g/L, nalidixic acid 0.01g/L, agar 14.0g/L
• Grams per litre: 43.00
• Litres per 500g: 12.00
• Plates per 500g: 630.00