Is Columbia CNA agar a defined or an undefined medium Provid

Is Columbia CNA agar a defined or an undefined medium? Provide the reasoning behind your choice and explain why this formulation is desirable. In your own words, what are the roles of colts tin and nalidixic acid in CNA and how does each work?

Solution

Columbia CNA agar is a type of selective medium which is used for growing Gram Positive Bacteria it usually contains two antibiotics colistin and naladixiv acid which inhibit the growth of Gram Negative bacteria.

Columbia blood Agar promotes luxuriant and Rapid growth of Gram Positive Bacteria and suppressinge the growth of most of the Gram Negative bacteria including pseudomonas ,klebsiella.

IT contains the ingredients like rt beef extract, yeast extract, sodium chloride, agar, nalidixic acid, colistin sulphate and animal products like sheep blood peptic digest of animal tissues, casein.

Columbia CNA agar is complex medium as it has the ingredients like beef extract blood along with the loan composition so this is a combination of both defined and undefined media.

2. Colistins and nalidixic acid are antibiotics which inhibit the growth of Gram Negative bacteria. Colistin contains poly cationic regionz that can invade outer membrane of Gram Negative bacterial cell wall as a result the outer membrane disrupt which leads to the lysis is of bacterial cell .

nalidixic acid inhabits the enzymes like topoisomerase and inhibits DNA replication there by inhabits the synthesis of DNA in Gram Negative bacteria.

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