Agar plate

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(Redirected from Blood agar)

Image:Agar plate with colonies.jpg An agar plate is a sterile Petri dish that contains agar plus nutrients (media) used to culture microorganisms. Generally, selective growth compounds are also added to the media, such as antibiotics.

For information on agar plate preparation, please visit the Wikibooks Agar Plate page.

1 Types of agar plates
2 References
3 See also
4 External links

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Types of agar plates

Image:Agarplates.jpg

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Blood agar types

Blood agar plate (BAP)

Contains blood from a mammal (usually sheep), typically at a concentration of 5–10%. BAP are an enriched, differential media used to isolate fastidious organisms and detect hemolytic activity. β-hemolytic activity will show complete lysis of red blood cells surrounding colony, while α-hemolysis will only partially lyse hemoglobin and will appear green. γ-hemolysis is the term referring to a lack of hemolytic activity.

Chocolate agar (CHOC)

A type of blood agar plate in which the blood cells have been lysed; used for growing fastidious (fussy) respiratory bacteria.

Thayer-Martin agar (TM)

Chocolate agar designed to isolate Neisseria gonorrhoeae.

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General bacterial media

Hektoen Enteric (HE)

HE agar is designed to isolate and recover fecal bacteria belonging to the Enterobacteriaceae family. HE is particularly useful in isolating Salmonella and Shigella.

MacConkey agar (MAC)

A selective and differential media used to differentiate between Gram negative bacteria while inhibiting the growth of Gram positive bacteria. The addition of bile salts and crystal violet to the agar inhibits the growth of most Gram positive bacteria, making MacConkey agar selective. Lactose and neutral red are added to differentiate the lactose fermenters, which form pink colonies, from lactose nonfermenters that form clear colonies.

Mannitol Salt Agar (MSA)

MSA is also a selective and differential media. Mannitol is the differential part, it indicates organisms that ferment mannitol. If mannitol fermentation is occurring, lactic acid will be produced, and the pH will drop causing the MSA plate to turn yellow. The salt portion is selective for halophiles; organisms that cannot withstand a high salt content will be unable to grow.

Neomycin agar

Contains the antibiotic neomycin.

Nutrient agar

Safe to use in school science laboratories because it does not selectively grow pathogenic bacteria.

Önöz agar

The most important advantage of this culture medium is that it allows more rapid bacteriological diagnosis as, Salmonella and Shigella colonies can be clearly and reliably differentiated from other Enterobacteriaceae. The yields of Salmonella from stool samples obtained, when using this medium, are higher than those obtained with LEIFSON Agar or Salmonella–Shigella agar (SSA).

Xylose-Lysine-Deoxycholate (XLD) agar.

XLD is used for the culture of stool samples, and contains two indicators. It is formulated to inhibit Gram-positive bacteria, while the growth of Gram-negative bacilli is encouraged. The colonies of lactose fermenters appear yellow.

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Fungal media

Sabouraud agar

Used to culture fungi, Sabouraud agar and has a low pH that inhibits the growth of most bacteria; also contains the antibiotic gentamicin to specifically inhibited the growth of Gram-negative bacteria.