Columbia CNA agar is a type of selective medium employed in culturing gram positive cocci and distincting it from clinical and nonclinical samples made up of a combined flora. Columbia CNA SHOULD NOT BE COMPARED with general culture medium such as the Nutrient agar which provides the necessary nutrients for the growth of diverse species of organisms.
Good growth stands for the growth of organisms picked or needed to culture with the required amount of colonies on Columbia CNA. Poor or no growth infers on the NA availability for the growth of the specimen organism, it is absent in the culture as it lacks the needed amount of colonies.
In conclusion, It may look good to look for the similarities and differences of the organisms to one another on the CNA plate since the NA plate is mainly the control and is used to evaluate the growth quality of the bacteria, contrasting it to the CNA plate is of no use as its main reason would be futile.
