Bacterial Growth on Agar Plates

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Questions and Answers

Which type of blood agar plate is specifically used to isolate Neisseria gonorrheae?

Standard blood agar plate
Thiosulfate citrate bile salts sucrose-enriched agar
Thayer-Martin agar (correct)
Chocolate agar

What is the primary purpose of a chocolate agar plate?

To culture fastidious respiratory bacteria (correct)
To enhance the growth of Vibrio species
To isolate hemolytic Streptococcal species
To detect lactose fermentation

Which agar plate is designed to enhance the growth of Vibrio species?

Thiosulfate citrate bile salts sucrose-enriched agar (correct)
Blood agar plate
Thayer-Martin agar
Chocolate agar

What distinguishes standard blood agar plates from chocolate agar?

<p>Chocolate agar is prepared by boiling blood cells (D)</p> Signup and view all the answers

Which of the following organisms is primarily detected using blood agar plates?

<p>Streptococcal species (C)</p> Signup and view all the answers

Flashcards

Blood agar plate

A type of agar plate used to cultivate fastidious organisms (organisms with complex nutritional needs) and to identify hemolytic activity (the ability of bacteria to break down red blood cells). This agar contains mammalian blood.

Chocolate agar

A type of blood agar where the blood cells have been lysed (broken down) by heating them to 56°C. This treatment releases nutrients that make it ideal for growing fastidious respiratory bacteria such as Haemophilus influenzae.

Thayer-Martin agar

A selective medium used to isolate Neisseria gonorrheae, a type of bacteria that causes gonorrhea. It's essentially a chocolate agar with additional ingredients to inhibit other bacteria and promote the growth of Neisseria.

Thiosulfate Citrate Bile Salts Sucrose (TCBS) Agar

A selective medium designed to enhance the growth of Vibrio species, particularly V. cholerae, the bacterium responsible for cholera. It contains thiosulfate, citrate, bile salts, and sucrose, which promote the growth of Vibrio while inhibiting others.

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Hemolytic Activity

The ability of some bacteria to break down red blood cells, leading to different patterns on the blood agar plate. Alpha hemolysis creates a greenish tint, beta hemolysis creates a clear zone, and gamma hemolysis shows no change.

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Study Notes

Blood Agar Plate Types

Blood agar plates contain mammalian blood, crucial for isolating difficult-to-grow organisms (fastidious organisms) and identifying hemolytic activity, particularly in Streptococcus species.

Chocolate Agar

Chocolate agar is a modified blood agar.
Blood cells are lysed by heating to 56°C.
This type of agar is used to culture fastidious respiratory bacteria, like Haemophilus influenzae.