Is pea selective or differential?

Phenylethyl alcohol agar (PEA) is a selective medium used to cultivate Gram positive organisms. The active ingredient, phenylethyl alcohol, inhibits or markedly reduces growth of Gram negative organisms by interfering with DNA synthesis. PEA also prevents Proteus species from swarming across the surface of the agar.

Is Pea blood agar selective?

Phenylethyl Alcohol Blood Agar (PEA) is an enriched selective medium used for the inhibition of facultative gram-negative rods and to inhibit the swarming of certain Clostridium species and Proteus species from clinical specimens.

Do gram-negative bacteria grow on pea?

Most gram-positive and gram-negative anaerobes grow on PEA agar medium, especially in mixed culture, and morphology of colonies is similar to that on blood agar plates, however, a longer incubation time is necessary to detect the more slowly growing and pigmented anaerobes (7).

Is Pea defined or undefined medium?

Is PEA a defined or an undefined medium? Provide the reasoning behind your choice and explain why this formulation is desirable. i. It is an undefined medium that contains more preformed nutrients/growth factors, so it better supports bacterial growth.

Is Pea positive or negative?

Phenylethyl Alcohol (PEA) Agar

Plate A is a PEA plate with a Gram positive organism on the left and a Gram negative organism on the right. Plate B is a nutrient agar plate illustrating normal growth of each of the same bacteria.

Is Mac selective or differential?

MacConkey Agar (MAC) is a selective and differential medium designed to isolate and differentiate enterics based on their ability to ferment lactose. Bile salts and crystal violet inhibit the growth of Gram positive organisms.

Is blood agar selective?

Blood agar is a non-selective medium that can be made selective for certain pathogens by the addition of antibiotics, chemicals or dyes.

Can defined media be selective?

Selective media are used to select for the growth of a particular "selected" microorganism. For example, if a certain microbe is resistant to aparticular antibiotic (e.g., novobiocin), then that antibiotic can be added to the medium in order to prevent other organisms, which are not resistant, from growing.

Does this negate the usefulness of PEA as a selective medium?

If you observed growth of gram-negative organisms on the PEA plate you inoculated, does this negate the usefulness of PEA as a selective medium? PEA is a selective medium and good base which inhibits growth of most gram-negative organisms. yes it halts the selectivness.

What is differential agar?

Differential Media

Blood agar is a differential medium that distinguishes bacterial species by their ability to break down the red blood cells included in the media. Blood agar is often used to distinguish between the different species of pathogenic Streptococcus bacteria.

What is pea selective for?

Protocols Phenylethyl Alcohol (PEA) Agar

Specifically, PEA agar is a selective medium that is used for the isolation of gram-positive Staphylococcus species and Streptococcus species from clinical specimens or specimens that contain mixtures of bacterial flora.

Is MSA selective or differential?

This type of medium is both selective and differential. The MSA will select for organisms such as Staphylococcus species which can live in areas of high salt concentration (plate on the left in the picture below).

What is the selective agent found in MSA?

Mannitol Salt Agar (MSA)

This is a medium that is both selective and differential. The high salt concentration (7.5%) is the selective ingredient. Staphylococcus species, which commonly inhabit human skin, can grow on this high salt concentration (left plate in picture below).

Is CNA selective or differential?

CNA is a selective, differential agar medium used for isolation of gram positive bacteria in a variety of specimen types.

What is Columbia CNA agar?

Columbia Agar Base is a nutrient-rich formula containing 5% defibrinated blood, which provides more nutrients and the ability to exhibit hemolytic reactions.

Why are crystal violet agar and 7.5% sodium chloride agar considered selective media?

Why are crystal violet agar and 7.5% sodium chloride agar considered selective media? They are used to select or isolate specific bacteria. Gram-positive organisms are very sensitive to the basic dye in CV. NaCL produces an osmotic environment not conductive for any organism besides halophiles.

Does E coli grow on pea agar?

Although gram-negative bacteria such as E. coli and Proteus species are inhibited on PEA Agar, prolonged incubation (≥ 72 hours) reduces the selectivity of the medium and may allow these organisms to grow.

Is nutrient agar defined or undefined?

A wider variety of microorganisms will grow on undefined media than on defined so most general purpose media, such as nutrient agar or tryptocase soy agar (TSA), are undefined.

Is mannitol salt agar a differential or selective medium explain?

Mannitol Salt Agar (MSA) is a selective and differential medium. The high concentration of salt (7.5%) selects for members of the genus Staphylococcus, since they can tolerate high saline levels.

Why is MacConkey agar selective?

This medium is both selective and differential. The selective ingredients are the bile salts and the dye, crystal violet which inhibit the growth of Gram-positive bacteria. The differential ingredient is lactose.

Is chocolate agar selective or differential?

Chocolate agar (CHOC) or chocolate blood agar (CBA), is a nonselective, enriched growth medium used for isolation of pathogenic bacteria. It is a variant of the blood agar plate, containing red blood cells that have been lysed by slowly heating to 80°C.

Is tryptic soy agar selective or differential?

Tryptic Soy Agar (TSA): a general purpose, non-selective, non-differential, supportive medium that supports growth of all microorganisms that do not require special nutrients.

Is sheep blood agar selective?

Grow a wide variety of fastidious organisms on Thermo Scientific™ Blood Agar (TSA with Sheep Blood), a general purpose non-selective medium with the addition of sheep blood in the formulation to promote the presence and visualization of haemolytic reactions so it can be used as a diagnostic tool.

What are the types of selective media?

Selective media

• Eosin methylene blue contains dyes that are toxic for Gram-positive bacteria. ...
• YM (yeast extract agar) has a low pH, deterring bacterial growth.
• MEA (malt extract agar) has a low pH, deterring bacterial growth.
• MacConkey agar is for Gram-negative bacteria.

What makes media selective or differential?

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.