Bacteria Of Clinical Significance: Part II Staphylococcus
This quiz focuses on Staphylococcus, exploring its hemolytic properties and mannitol salt fermentation. It assesses understanding of bacterial behavior in clinical settings, differentiating species based on growth media reactions. Essential for students and professionals in microbiology and healthcare.
- 1.
Beta hemolysis
- A.
Incomplete lysis of the RBCs (green tint to the media)
- B.
Complete lysis of the RBCs (complete clearing of the media)
- C.
No lysis of the RBCs (no hemolysis)
Correct Answer
B. Complete lysis of the RBCs (complete clearing of the media)Explanation
Beta hemolysis refers to the complete lysis of red blood cells (RBCs), which is characterized by the complete clearing of the media. This means that the bacteria or organism being tested has the ability to completely break down the RBCs, resulting in the clearing of the media around the bacterial growth. This is in contrast to alpha hemolysis, which is characterized by incomplete lysis of the RBCs and results in a green tint to the media, and gamma hemolysis, which is characterized by no lysis of the RBCs and no hemolysis observed.Rate this question:
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- 2.
Alpha hemolysis:
- A.
Incomplete lysis of the RBCs (green tint to the media)
- B.
Complete lysis of the RBCs (complete clearing of the media)
- C.
No lysis of the RBCs (no hemolysis)
Correct Answer
A. Incomplete lysis of the RBCs (green tint to the media)Explanation
Alpha hemolysis refers to the incomplete lysis of red blood cells (RBCs) in a culture medium. This is characterized by a green tint to the media. It means that the bacteria present in the culture are able to partially break down the RBCs, resulting in a greenish discoloration of the surrounding medium. This is in contrast to complete lysis of the RBCs, which would result in a clear or transparent appearance of the media, or no lysis of the RBCs, which would show no change in color or appearance.Rate this question:
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- 3.
Non-hemolytic:
- A.
Incomplete lysis of the RBCs (green tint to the media)
- B.
Complete lysis of the RBCs (complete clearing of the media)
- C.
No lysis of the RBCs (no hemolysis)
Correct Answer
C. No lysis of the RBCs (no hemolysis)Explanation
The correct answer is "no lysis of the RBCs (no hemolysis)". This means that there is no breakdown or destruction of the red blood cells in the media. The media remains unchanged and there is no visible evidence of hemolysis.Rate this question:
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- 4.
Mannitol salt fermentation:
- A.
Mannitol Salt Agar is a selective and differential media. It selects for the growth of Staphylococcus sp. while it inhibits the growth of other organisms due to its elevated salt concentration (7.5% NaCl). It differentiates Staphylococcus sp. based on mannitol fermentation.
- B.
Detects free coagulase which is an extracellular protein excreted by the organism that causes fibrin clot formation. This is a key differential test for the identification of Staphylococcus aureus.
- C.
Key differential test for identification of S. saprophyticus Procedure
Correct Answer
A. Mannitol Salt Agar is a selective and differential media. It selects for the growth of Staphylococcus sp. while it inhibits the growth of other organisms due to its elevated salt concentration (7.5% NaCl). It differentiates Staphylococcus sp. based on mannitol fermentation.Explanation
Mannitol Salt Agar is a selective and differential media that allows for the growth of Staphylococcus species while inhibiting the growth of other organisms due to its high salt concentration. It also differentiates Staphylococcus species based on their ability to ferment mannitol. This means that if a Staphylococcus species is able to ferment mannitol, it will produce acid, causing a change in the color of the agar from red to yellow. This makes it a useful tool for identifying Staphylococcus aureus, as it is one of the few species that can ferment mannitol.Rate this question:
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- 5.
Positive
- A.
No coagulation or clot formation
- B.
Red colony/no color change around colony
- C.
Yellow colony/yellow area around colon
Correct Answer
C. Yellow colony/yellow area around colonExplanation
The correct answer is yellow colony/yellow area around the colon. This indicates that there is a presence of a specific type of bacteria that produces a yellow pigment. This can be helpful in identifying the bacteria and determining its characteristics. The other options, such as no coagulation or clot formation and red colony/no color change around the colony, do not provide any specific information about the bacteria present.Rate this question:
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- 6.
Negative:
- A.
Yellow colony/yellow area around colony
- B.
Red colony/no color change around colony
- C.
No coagulation or clot formation
Correct Answer
B. Red colony/no color change around colonyExplanation
The correct answer is red colony/no color change around colony. This indicates that there was no color change or reaction around the colony, suggesting that there was no coagulation or clot formation. The absence of any visible change in the surrounding area indicates a negative result.Rate this question:
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- 7.
Tube coagulase
- A.
- detects free coagulase which is an extracellular protein excreted by the organism that causes fibrin clot formation. This is a key differential test for the identification of Staphylococcus aureus.
- B.
Mannitol Salt Agar is a selective and differential media. It selects for the growth of Staphylococcus sp. while it inhibits the growth of other organisms due to its elevated salt concentration (7.5% NaCl). It differentiates Staphylococcus sp. based on mannitol fermentation.
- C.
Key differential test for identification of S. saprophyticus Procedure
Correct Answer
A. - detects free coagulase which is an extracellular protein excreted by the organism that causes fibrin clot formation. This is a key differential test for the identification of Staphylococcus aureus. -
- 8.
Positive:
- A.
Coagulation of the plasma (clot formation). Note: any degree of coagulation is considered positive.
- B.
Yellow colony/yellow area around colony
- C.
Red agglutination with a blue background
Correct Answer
A. Coagulation of the plasma (clot formation). Note: any degree of coagulation is considered positive.Explanation
The correct answer is coagulation of the plasma (clot formation). This means that when the plasma coagulates or forms a clot, it is considered positive. It is important to note that any degree of coagulation is considered positive in this context. The other options mentioned, such as yellow colony/area around the colony and red agglutination with a blue background, are not relevant to the concept of coagulation of plasma.Rate this question:
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- 9.
Negative:
- A.
Red agglutination with a blue background
- B.
Yellow colony/yellow area around colony
- C.
No coagulation or clot formation
Correct Answer
C. No coagulation or clot formationExplanation
The given answer states that there is no coagulation or clot formation. This suggests that the test being described does not result in the formation of a clot or coagulation. The other information provided, such as red agglutination with a blue background and yellow colony/area around the colony, does not contradict this answer or provide any indication of clot formation. Therefore, the absence of clot formation is the most accurate explanation based on the given information.Rate this question:
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- 10.
Novobiocin inhibition test
- A.
Detects free coagulase which is an extracellular protein excreted by the organism that causes fibrin clot formation.
- B.
Key differential test for identification of S. saprophyticus
- C.
Mannitol Salt Agar is a selective and differential media. It selects for the growth of Staphylococcus sp. while it inhibits the growth of other organisms due to its elevated salt concentration (7.5% NaCl). It differentiates Staphylococcus sp. based on mannitol fermentation.
Correct Answer
B. Key differential test for identification of S. saprophyticusExplanation
The Novobiocin inhibition test is a key differential test used to identify S. saprophyticus. This test detects the presence of free coagulase, which is an extracellular protein produced by the organism. S. saprophyticus is the only species of Staphylococcus that is coagulase-negative, meaning it does not produce coagulase. Therefore, if the Novobiocin inhibition test shows inhibition of coagulase activity, it indicates that the organism is likely S. saprophyticus. This test is important for distinguishing S. saprophyticus from other species of Staphylococcus.Rate this question:
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- 11.
Negative
- A.
>= 17 mm Susceptible
- B.
Correct Answer
A. >= 17 mm SusceptibleExplanation
The given statement suggests that if the measurement is greater than or equal to 17 mm, it indicates susceptibility. This means that any value equal to or greater than 17 mm would be considered as susceptible.Rate this question:
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- 12.
Positive
- A.
>= 17 mm Susceptible
- B.
Correct Answer
B. -
- 13.
Sure-Vue Color Staph Identification Test Kit
- A.
This is a rapid latex slide agglutination test that utilizes protein-coated latex particles to detect coagulase (clumping factor) and/or Protein A that are characteristics associated with Staphylococcus aureus.
- B.
Key differential test for identification of S. saprophyticus
- C.
This is a key differential test for the identification of Staphylococcus aureus.
Correct Answer
A. This is a rapid latex slide agglutination test that utilizes protein-coated latex particles to detect coagulase (clumping factor) and/or Protein A that are characteristics associated with Staphylococcus aureus.Explanation
The Sure-Vue Color Staph Identification Test Kit is a rapid latex slide agglutination test that uses protein-coated latex particles to detect coagulase and/or Protein A, which are characteristics associated with Staphylococcus aureus. This test is specifically used as a key differential test for the identification of Staphylococcus aureus.Rate this question:
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- 14.
Positive reaction:
- A.
Red agglutination with a blue background
- B.
No agglutination
Correct Answer
A. Red agglutination with a blue backgroundExplanation
The correct answer is "Red agglutination with a blue background" because it indicates a positive reaction. This means that the substance being tested has caused the particles to clump together, resulting in a visible red agglutination. The blue background is likely used to enhance the contrast and make the agglutination more easily visible. The absence of agglutination would indicate a negative reaction, where the particles remain dispersed and do not clump together.Rate this question:
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- 15.
Negative reaction:
- A.
Red agglutination with a blue background
- B.
No agglutination
Correct Answer
B. No agglutinationExplanation
The correct answer is "No agglutination." This means that there was no clumping or aggregation of particles observed in the test. This could indicate that the reaction did not occur or that the antibodies and antigens did not interact with each other.Rate this question:
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Current Version
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Jan 18, 2023Quiz Edited by
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Nov 10, 2010Quiz Created by
Maer