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Questions and Answers
What is the purpose of adding mammalian blood to the blood agar base?
What is the purpose of adding mammalian blood to the blood agar base?
The addition of mammalian blood allows for the isolation, cultivation, and detection of hemolytic activity of certain microorganisms.
Describe the difference between alpha-hemolysis and beta-hemolysis in blood agar.
Describe the difference between alpha-hemolysis and beta-hemolysis in blood agar.
Alpha-hemolysis partially lyses red blood cells, appearing green, while beta-hemolysis completely lyses red blood cells, showing clear zones around colonies.
What are the control organisms typically used to assess growth and hemolytic activity on blood agar?
What are the control organisms typically used to assess growth and hemolytic activity on blood agar?
Streptococcus pneumoniae is used for alpha-hemolysis, and Streptococcus pyogenes is used for beta-hemolysis.
Explain the significance of autoclaving the blood agar medium during preparation.
Explain the significance of autoclaving the blood agar medium during preparation.
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What is the appearance of gamma-hemolysis on blood agar?
What is the appearance of gamma-hemolysis on blood agar?
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Blood agar contains mammalian ______, typically at a concentration of 5–10%.
Blood agar contains mammalian ______, typically at a concentration of 5–10%.
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The procedure for preparing blood agar requires autoclaving at 15lbs pressure and ______°C for 15 minutes.
The procedure for preparing blood agar requires autoclaving at 15lbs pressure and ______°C for 15 minutes.
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α-hemolysis will appear ______ on blood agar due to partial lysis of red blood cells.
α-hemolysis will appear ______ on blood agar due to partial lysis of red blood cells.
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β-hemolysis shows complete digestion of red blood cell contents, indicating ______ growth.
β-hemolysis shows complete digestion of red blood cell contents, indicating ______ growth.
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γ-hemolysis refers to a lack of ______ activity.
γ-hemolysis refers to a lack of ______ activity.
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Study Notes
Blood Agar Preparation
- Blood agar is a culture medium made with mammalian blood (usually sheep or horse).
- The blood concentration is typically 5-10%.
Preparation Procedure
- Dissolve 40g of blood agar base in 1000ml of distilled water by heating to boiling.
- Sterilize the medium by autoclaving at 15lbs pressure, 121°C for 15 minutes.
- Cool the medium to 45-50°C.
- Add 5-10% mammalian blood and pour into sterile Petri dishes.
Uses of Blood Agar
- Used to isolate, cultivate, and detect hemolytic activity of streptococci, pneumococci, and other demanding microorganisms.
Control Organisms and Hemolysis
- Streptococcus pneumoniae: Good growth, alpha-hemolysis (green color).
- Streptococcus pyogenes: Good growth, beta-hemolysis (clear zone around colony).
- Alpha-hemolysis partially degrades hemoglobin, creating a green appearance.
- Beta-hemolysis completely lysing and digests red blood cells, creating a clear zone.
- Gamma-hemolysis (non-hemolytic) indicates a lack of hemolytic activity.
Diagnosing Infection
- Blood agar plates are commonly used to diagnose infections.
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Description
This quiz covers the preparation procedure, applications, and characteristics of blood agar as a culture medium. Learn about the specific hemolytic activities of various microorganisms and their classification. Test your knowledge on how to properly prepare and utilize blood agar in microbiology.
