What is the purpose of Columbia CNA with 5 sheep blood agar?

BD Columbia CNA Agar with 5% Sheep Blood is a selective medium used for the isolation of gram-positive bacteria (especially staphylococci and streptococci) from clinical specimens. *Adjusted and/or supplemented as required to meet performance criteria.

What is the role of sheep blood in CNA agar?

Columbia CNA Agar has traditionally been used to identify staphylococci and streptococci. The addition of sheep blood to the medium allows distinct identification of S. pneumoniae through the production of clear alpha-haemolysis.

How does Columbia CNA agar work?

Columbia-CNA Agar (C-CNA) is a type of selective media which selects for Gram-positive bacteria. It contains two antibiotics, colistin and naladixic acid, which inhibit the growth of gram-negative bacteria, thus selecting for Gram-positive organisms.

What is Columbia blood agar used for?

BD Columbia Agar with 5% Sheep Blood is a primary isolation medium on which most microorganisms, such as Enterobacteriaceae, Pseudomonas and other non-fermenting Gram negative rods, streptococci, enterococci, staphylococci, coryneforms, Candida species, and many others will grow.

What is the key ingredient that makes Columbia blood agar differential?

The addition of antimicrobial agents, colistin (or polymyxin B) and nalidixic acid, makes the medium selective for gram-positive microorganisms. Colistin and nalidixic acid disrupt the cell membrane of gram-negative organisms, while nalidixic acid blocks DNA replication in susceptible gram-negative bacteria.

What is the key ingredient that makes Columbia blood agar selective?

Columbia-CNA Agar (C-CNA) is a type of selective and differential media which selects for Gram-positive bacteria. Selective ingredients: It contains two antibiotics, colistin and naladixic acid, which inhibit the growth of gram-negative bacteria, thus selecting for Gram-positive organisms.

Is CNA blood agar selective or differential?

differential

The CNA-blood agar, like the TSA-blood agar is differential. The differential material in both is defibrinated red blood cells.

What does the presence of colistin and the nalidixic acid within the Columbia CNA blood agar do to gram-negative bacteria?

The addition of Colistin and Nalidixic Acid inhibits growth of gram negative organisms.