page 95
Purpose :
The purpose of acid-fast staining is to identify acid-fast organisms that belongs to genus mycobacterium.
pg 96 (Yoli)
Questions
1. What are the large stained areas on the sputum slide?
- Mainly white blood cells and non acid-fast organisms
2. What is the decolorizing agent in the gram stain?-Ethanol2b. In the acid-fast stain?
- Acid alcohol
3. What diseases are diagnosed using the acid-fast stain?
-Tuberculosis (caused by Mycobacterium tuberculosis), Leprosy, Nacordiosis.
4. What is phenol (carbolic acid), and what is its usual application?
-Phenol is an alcohol with a benzene ring attached. It s an aromatic compound and it is used as a disinfectant because it controls the growth microorganisms.
Critical Thinking!
1. Assuming you could stain any cell, would an acid-fast organism be gram-positive or gram-negative? Explain.
-It would be gram positive (a weak or abnormal gram positive) because acid-fast organism have a wax-like lipid called mycolic acid that makes them impermeable to most stains, it won't pick up the blue/purple color correctly but the color that it does pick up it won't be decolorized at all by the decolorizing agent so it would give a weak positive gram result.
2. How do the acid-fast properties relate to the gram stain?
-Acid-fast organism retain the primary stain even after the decolorizing agent, Gram-positive also retains the primary stain after the decolorizing agent and Gram-negative would lose the primary stain when washed with the ethanol. Acid-fast staining is used to differentiate between different types of bacteria, which is the same use of the gram stain.
3.Clinical specimens suspected of containing Mycobacterium are digested with sodium hydroxide (NaOH) for 30 minutes prior to staining. Why is this technique used? Why isn't this technique used for staining other bacteria?
-Its used to remove debris and contaminating bacterias. This technique cannot be used for staining other bacterias because they would be killed in the process, acid-fast bacteria have a really strong and impermeable wall and it won't be killed with the sodium hydroxide.
Chapter 12 - page 102, 103 Janelly
PAGE 102 & 103
1. Why is heat necessary in spore staining?
Heat is necessary in spore staining because it is important that heat penetrates the endospore wall. Therefore, the imperiate coat that spores contain around them can loosen up the cortex and allow it to accept the stain.
2. Explain the function of water in spore staining.
The function of water in spore staining is to decolorize the vegative components. It also washes off the excess primary stain, but not the spore.
3. A.) Tap water is normally used as the decolorizing agent to wash off excess stain. When using acid-alcohol, it decolorizes the cells and results in removing the stain.
B.) When you use safranin as the primary stain and malachite green as the secondary stain, the cells will stain green.
C.) When heat is not applied during the primary stain, the spores are not stained and t hey appear colorless.
4. Explain the medical significance of a capsule.
Capsules essentially “hide” the bacteria. Encapsulated bacterial cells generally have greater pathogenicity because capsules protect the bacteria against phagocytes, so that the WBC's can't attack it. It is also used for biofilms, which can form on non-living materials in catheters, IUD's and pacemakers.
5. Explain the function of copper sulfate in this procedure.
The function of copper sulfate in this procedure is that it is used as a decolorizing agent that washes away the purple primary stain out of the capsule.
Show less1. Why is heat necessary in spore staining?
Heat is necessary in spore staining because it is important that heat penetrates the endospore wall. Therefore, the imperiate coat that spores contain around them can loosen up the cortex and allow it to accept the stain.
2. Explain the function of water in spore staining.
The function of water in spore staining is to decolorize the vegative components. It also washes off the excess primary stain, but not the spore.
3. A.) Tap water is normally used as the decolorizing agent to wash off excess stain. When using acid-alcohol, it decolorizes the cells and results in removing the stain.
B.) When you use safranin as the primary stain and malachite green as the secondary stain, the cells will stain green.
C.) When heat is not applied during the primary stain, the spores are not stained and t hey appear colorless.
4. Explain the medical significance of a capsule.
Capsules essentially “hide” the bacteria. Encapsulated bacterial cells generally have greater pathogenicity because capsules protect the bacteria against phagocytes, so that the WBC's can't attack it. It is also used for biofilms, which can form on non-living materials in catheters, IUD's and pacemakers.
5. Explain the function of copper sulfate in this procedure.
The function of copper sulfate in this procedure is that it is used as a decolorizing agent that washes away the purple primary stain out of the capsule.
Chapter 113 - page 107 Lupe
2. The microscopic appearance of S. aureus is a dark purple color hue and it's shape and appearance is considered coccobacillus (a cluster of irregular cells). The appearance of E. coli is of white color hue and it is single bacillus (irregular single cells). The last one, B. cereus is of dark purple color hue and its arrangement is single bacillus.
1. No methylene blue cannot be used in place of nigrosin for negative staining. Methylene blue is is a basic stain that is positively charged. Negative staining requires an acidic stain that is negatively charged.
2. The advantages of negative staining are that it does not require heat fixing, cell is highlighted which makes it easier to see, and it is simple and quick.
3. The bacteria remains unstained, because with negative staining, the staining will occur around the organism.
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