Homework answers / question archive / University of Texas, Brownsville - CLSC 2429  Exercise 4: Gram Stain 1)What is the function of the iodine solution in the Gram stain? If it were omitted, how would staining results be affected? What is the purpose of the alcohol solution in the Gram stain? What counterstain is used? Why is it necessary? Could colors other than red be used? If your control smear does not show gram-positive cocci and gram-negative rods, can you assume that the Gram-stain reaction of your “test” organism is correct? Why? On the basis of Gram-stain reaction, can you distinguish species of: What is the size of staphylococci in micrometers? In centimeters? What is the advantage of the Gram stain over a simple stain such as methylene blue? In what kind of clinical situation would a direct smear report from the laboratory be of urgent importance? What is the current theory about the mechanism of the Gram-strain reaction?  

University of Texas, Brownsville - CLSC 2429  Exercise 4: Gram Stain 1)What is the function of the iodine solution in the Gram stain? If it were omitted, how would staining results be affected? What is the purpose of the alcohol solution in the Gram stain? What counterstain is used? Why is it necessary? Could colors other than red be used? If your control smear does not show gram-positive cocci and gram-negative rods, can you assume that the Gram-stain reaction of your “test” organism is correct? Why? On the basis of Gram-stain reaction, can you distinguish species of: What is the size of staphylococci in micrometers? In centimeters? What is the advantage of the Gram stain over a simple stain such as methylene blue? In what kind of clinical situation would a direct smear report from the laboratory be of urgent importance? What is the current theory about the mechanism of the Gram-strain reaction?  

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University of Texas, Brownsville - CLSC 2429

 Exercise 4: Gram Stain

1)What is the function of the iodine solution in the Gram stain? If it were omitted, how would staining results be affected?

2. What is the purpose of the alcohol solution in the Gram stain?
3. What counterstain is used? Why is it necessary? Could colors other than red be used?
4. If your control smear does not show gram-positive cocci and gram-negative rods, can you assume that the Gram-stain reaction of your “test” organism is correct? Why?
5. On the basis of Gram-stain reaction, can you distinguish species of:
6. What is the size of staphylococci in micrometers? In centimeters?
7. What is the advantage of the Gram stain over a simple stain such as methylene blue?
8. In what kind of clinical situation would a direct smear report from the laboratory be of urgent importance?
9. What is the current theory about the mechanism of the Gram-strain reaction?

 

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10.

Describe at least two conditions in which an organism might strain gram variable?

Exercise 5: Acid-Fast Stain

1.

What is a differential stain? Name two examples of such stains.

 

 

 

2.

Is a Gram stain adequate substitute for an acid-fast stain? Why?

3.

When is it appropriate to ask the laboratory to perform an acid-fast stain?

4.

Are saprophytic mycobacteria acid fast?

5.

Does the presence of acid-fast organisms in a clinical specimen always suggest serious

clinical disease?

6.

How should the acid-fast stain of a sputum specimen from a patient with suspected

pulmonary Nocardia infection be performed?

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