Question: Why Blood Agar Is Selective Media?

Why is blood agar not a selective media?

Blood agar is an enriched medium that provides an extra rich nutrient environment for microbes.

Therefore, BAP is not a selective growth medium, since it supports the growth of a wide range of organisms..

What is the selective agent in blood agar?

colistenCNA-blood agar contains the selective agents colisten and nalidixic acid. Colisten negatively affects the cell membrane of many Gram(-) species, and nalidixic acid inhibits replication of DNA in susceptible species. The result is that CNA-blood selects for Gram(+) coccus-shaped species, and against everything else.

What types of bacteria grow on blood agar?

Blood Agar is used to grow a wide range of pathogens particularly those that are more difficult to grow such as Haemophilus influenzae, Streptococcus pneumoniae and Neisseria species. It is also required to detect and differentiate haemolytic bacteria, especially Streptococcus species.

What is the principle of blood agar?

Blood Agar is a general-purpose enriched medium used to grow fastidious organisms and to differentiate bacteria based on their hemolytic properties. It is a highly nutritious medium generally used as a basal medium for preparing blood agar by supplementation with blood.

What is the purpose of blood agar?

Many species of bacteria produce toxic by-products that are capable of destroying red blood cells. Blood agar is a general purpose enriched medium often used to grow fastidious organisms and to differentiate bacteria based on their hemolytic properties.

How do bacteria grow on agar?

Agar is a compound that is derived from algae. It contains many nutrients, and bacteria can thrive on it. It is gelatinous, and is created by mixing powdered agar with water and adding heat. … After this liquid is poured into sterile Petri dishes, it solidifies into a gel and can be used as a medium for bacterial growth.

What is the difference between blood agar and chocolate agar?

The composition of chocolate agar and the Blood Agar is the same and the only difference is while preparing chocolate agar, the red blood cells are lysed. … Neither of these species is able to grow on sheep blood agar. Chocolate agar slants are used for the short-term storage of pathogens such as N.

Is blood agar a selective media?

Examples include sheep blood agar and chocolate (heated blood) agar. Selective media contain ingredients that inhibit the growth of some organisms but allow others to grow. … Blood agar is one type of differential medium, allowing bacteria to be distinguished by the type of hemolysis produced (see below).

What makes a media selective?

Selective and differential media are used to isolate or identify particular organisms. Selective media allow certain types of organisms to grow, and inhibit the growth of other organisms. … For example, organisms that can utilize a given sugar are easily screened by making that sugar the only carbon source in the medium.

What Bacteria grows on MacConkey Agar?

Altogether, MacConkey agar only grows gram-negative bacteria, and those bacteria will appear differently based on their lactose fermenting ability as well as the rate of fermentation and the presence of a capsule or not.

What color is E coli on blood agar?

E. coli appears as purple-blue colored colonies on the BluEcoli™ Agar side of the biplate. Other gram-negative rods that grow on the BluEcoli™ Agar side may appear pink to slight pink for lactose-positive colonies, and colorless for lactose-negative colonies, as is typical of MacConkey Agar.

Can salmonella grow on blood agar?

Blood agar – Colonies are moist and 2-3mm in diameter. CLED agar – Salmonella species are lactose non fermenters (some serotypes e.g. Salmonella Arizonae and Salmonella Indiana may ferment lactose).

What bacteria does not grow on blood agar?

Blood agar is an enriched, bacterial growth medium. Fastidious organisms, such as streptococci, do not grow well on ordinary growth media. Blood agar is a type of growth medium (trypticase soy agar enriched with 5% sheep blood) that encourages the growth of bacteria, such as streptococci, that otherwise wouldn’t grow.

Is chocolate agar selective or differential?

Chocolate agar, a differential medium for gram-positive cocci. Journal of Clinical Microbiology.

What is the purpose of selective media?

Selective media generally selects for the growth of a desired organism, stopping the growth of or altogether killing non-desired organisms. Differential media takes advantage of biochemical properties of target organisms, often leading to a visible change when growth of target organisms are present.