Quick Answer: Why Do We Use Chocolate Agar?

What bacteria only grows on chocolate agar?

Chocolate agar contains blood that has been heated to release factors that aid in the growth of fastidious bacteria, most notably Haemophilus and Neisseria species..

What grows MacConkey Agar?

MacConkey agar is a selective and differentiating agar that only grows gram-negative bacterial species; it can further differentiate the gram-negative organisms based on their lactose metabolism.

How do you interpret MacConkey Agar?

Result Interpretation on MacConkey Agar Lactose fermenting strains grow as red or pink and may be surrounded by a zone of acid precipitated bile. The red colour is due to production of acid from lactose, absorption of neutral red and a subsequent colour change of the dye when the pH of medium falls below 6.8.

What Colour is MacConkey Agar?

pinkMacConkey agar with LF and non-LF colonies. The organism on the left is a lactose fermenter, as evidenced by the pink color.

What bacteria Cannot 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.

What is the purpose of differential media?

Differential media are used to differentiate closely related organisms or groups of organisms. Owing to the presence of certain dyes or chemicals in the media, the organisms will produce characteristic changes or growth patterns that are used for identification or differentiation.

Does bacteria grow on chocolate?

“The good microbes, such as Bifidobacterium and lactic acid bacteria, feast on chocolate,” she said. “When you eat dark chocolate, they grow and ferment it, producing compounds that are anti-inflammatory,” said John Finley, Ph.

Why is human blood not used in blood agar?

However, the use of easily available human blood for blood agar is discouraged because of the common tenet that human blood in nutrient media results in poor bacterial isolation rates and hardly visible hemolysis or no hemolysis at all.

Is blood agar selective?

Blood Agar Is Not a Selective Medium 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 major difference between blood agar and chocolate agar?

Chocolate agar is used for the isolation of fastidious organisms, such as Haemophilus influenzae, when incubated at 35-37°C in a 5% CO2 atmosphere. 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.

Is chocolate agar a differential media?

Chocolate agar, a differential medium for gram-positive cocci.

What is the use of blood agar?

Blood agar is a general purpose enriched medium often used to grow fastidious organisms and to differentiate bacteria based on their hemolytic properties.

Why is blood agar used to grow throat cultures?

Blood agar plates are routinely used in the clinic to test for pathenogenic bacteria in throat swabs. These throat pathogens are often Gram positive cocci that may be hemolytic, producing exotoxins called hemolysins that destroy blood cells.

Does chlamydia grow on chocolate agar?

Chlamydia species are obligate intracellular bacteria that require growth inside mammalian cells for propagation and survival. As a result, Chlamydia cannot be grown on conventional bacteriological medium. This property makes Chlamydia difficult organisms to grow and maintain in the laboratory.

What is the difference between selective and differential agar?

Selective media favor the growth of some microorganisms while inhibiting others. Differential media help distinguish bacteria by the color of the colonies or the change in the medium.

What is an example of differential media?

Examples of differential media include: Blood agar (used in strep tests), which contains bovine heart blood that becomes transparent in the presence of hemolytic. … MacConkey (MCK), which is differential for lactose fermentationmannitol salt agar (MSA), which is differential for mannitol fermentation.

What type of media is 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.

Why Alpha hemolysis is green?

Alpha-hemolysin partially breaks down the red blood cells and leaves a greenish color behind. This is referred to as α-hemolysis (alpha hemolysis). The greenish color is caused by the presence of biliverdin, which is a by-product of the breakdown of hemoglobin.