In your own words, what is thw application of columbia CNA with 5% sheep blood agar? Solution Columbia CNA with 5% Sheep blood agar is a kind of selective as well as differential meadium. Mainly this is used for culture if Gram positive bacteria. In this media, differential growth of Entericocci, Staphylococci , hemolytic streptococci occurs while some clinical isolates like Klebsiella, Pseudomonas and Proteus are inhibited. Therefire this media is also used as differential medium. The differential selection occurs on the basis of hemolytic reactions..