What are the steps of the Gram stain procedure?
The performance of the Gram Stain on any sample requires four basic steps that include applying a primary stain (crystal violet) to a heat-fixed smear, followed by the addition of a mordant (Gram’s Iodine), rapid decolorization with alcohol, acetone, or a mixture of alcohol and acetone and lastly, counterstaining with …
What is Gram staining and explain its procedure?
The Gram stain procedure distinguishes between Gram positive and Gram negative groups by coloring these cells red or violet. Gram positive bacteria stain violet due to the presence of a thick layer of peptidoglycan in their cell walls, which retains the crystal violet these cells are stained with.
What is the most important step in Gram staining?
The thickness of the smear used in the Gram stain will affect the result of the stain. The step that is most crucial in effecting the outcome of the stain is the decolorizing step.
What are the steps of Gram staining quizlet?
Terms in this set (4)
- Gram Staining – Step 1. Flood heat-fixed emulsion with Crystal Violet, let stand for 1 minute, rinse with water.
- Gram Staining – Step 2. Add iodine solution, let stand for 1 minute, rinse with water.
- Gram Staining – Step 3.
- Gram Staining – Step 4.
What are the differences between Gram positive and negative bacteria?
Gram positive bacteria have a thick peptidoglycan layer and no outer lipid membrane whilst Gram negative bacteria have a thin peptidoglycan layer and have an outer lipid membrane.
What do the Gram stain and acid fast stain have in common?
-Heat fix slide. What do the Gram stain, acid-fast stain, and endospore stain have in common? They use a negative stain technique. They use heat to force the dye into cell structures.
What is the importance of acid fast staining?
The acid-fast stain is a laboratory test that determines if a sample of tissue, blood, or other body substance is infected with the bacteria that causes tuberculosis (TB) and other illnesses.
What is the difference between Gram stain and acid fast stain?
The main difference between Gram stain and acid fast stain is that Gram stain helps to distinguish bacteria with different types of cell walls whereas acid-fast stain helps to distinguish Gram-positive bacteria with waxy mycolic acids in their cell walls.
What are the advantages of using stains in microbiology?
The most basic reason that cells are stained is to enhance visualization of the cell or certain cellular components under a microscope. Cells may also be stained to highlight metabolic processes or to differentiate between live and dead cells in a sample.
What are the advantages of Gram staining?
List of Advantages of Gram Staining
- It gives quick results when examining infections.
- It is simple and cost-effective.
- It helps with determining appropriate treatments for infection.
- It allows for various methods of testing.
- It is basically a key procedure in identifying bacteria.
What is purpose of staining?
The main reason you stain a specimen before putting it under the microscope is to get a better look at it, but staining does much more than simply highlight the outlines of cells. Some stains can penetrate cell walls and highlight cell components, and this can help scientists visualize metabolic processes.
What is the importance of staining?
Staining is used to highlight important features of the tissue as well as to enhance the tissue contrast. Hematoxylin is a basic dye that is commonly used in this process and stains the nuclei giving it a bluish color while eosin (another stain dye used in histology) stains the cell’s nucleus giving it a pinkish stain.
What are the types of staining?
- Types of staining techniques. Simple staining.
- Differential staining. (Use of of single stain)
- (Use of two contrasting stains) Direct.
- Indirect. Separation.
- Visualization. (Positive)
- (Negative) into groups. of structures.
- Gram stain. Flagella stain.
- Acid fast. Capsule stain.
What is staining and its types?
The types are: 1. Simple Staining 2. Gram Staining 4. Acid Fast Staining 5. Endospore Staining.
What is the principle of staining?
The staining is the combination of a coloured substance (dye) with the tissue that retains the dye after washing. The staining is primarily a chemical reaction between the dye and the tissue. The following chemical reactions are involved between the dye and tissue components (Box 7.1) [1, 2]:
Why 95 Ethanol is used in Gram staining?
Remel Gram Decolorizer (95% Ethyl Alcohol) is a reagent recommended for use in qualitative procedures to differentiate gram-negative from gram- positive organisms. The primary stain, crystal violet, is a basic dye which rapidly permeates the cell wall of all bacteria, staining the protoplast purple.
What is known as the principal stain?
Crystal Violet, the primary stain. Iodine, the mordant. A decolorizer made of acetone and alcohol (95%)
What is the principle of acid fast staining?
Principle of acid fast staining (in mycobacteria): Heat softens the wax in the cell wall and allows the stain (basic fuchsin) to enter. The fuchsin dye is more soluble in phenol than in water or alcohol. Phenol in turn is more soluble in lipids or waxes, thus the dye-phenol mixture enters the cell.
What are examples of acid fast bacteria?
Common acid-fast bacteria of medical importance include Mycobacterium tuberculosis, Mycobacterium leprae,Mycobacterium avium-intracellulare complex, and Nocardia species.
What is the role of phenol in acid fast staining?
In acid fast stains, the phenol allows the stain to pen- etrate, even after exposure to decolourisors. If an organism is to be termed Acid Fast, it must resist decolourisation by acid-alcohol. A counterstain is then used to emphasise the stained organism.
Are acid fast bacteria Gram-positive or negative?
Acid-fast bacteria are gram-positive in terms of structure because they contain peptidoglycan in the cell wall. However, they stain poorly with Gram stain procedure, appearing weakly Gram-positive.
What bacteria Cannot be Gram stained?
Atypical bacteria are bacteria that do not color with gram-staining but rather remain colorless: they are neither Gram-positive nor Gram-negative. These include the Chlamydiaceae, Legionella and the Mycoplasmataceae (including mycoplasma and ureaplasma); the Rickettsiaceae are also often considered atypical.
Why acid fast bacteria Cannot be Gram stained?
Mycobacteria are “Acid Fast” They cannot be stained by the Gram stain because of their high lipid content. 2. Acid fast staining is used to stain mycobacteria. Bacteria are treated with a red dye (fuchsin) and steamed.
What happens if AFB is positive?
A positive AFB smear or culture several weeks after drug treatment has started may mean that the treatment regimen is not effective and needs to be changed. It also means that the person is still likely to be infectious and can pass the mycobacteria to others through coughing or sneezing.
Does AFB positive mean TB?
If your AFB smear was positive, it means you probably have TB or other infection, but an AFB culture is needed confirm the diagnosis. Culture results can take several weeks, so your provider may decide to treat your infection in the meantime.
Is TB Gram positive or negative?
Mycobacterium tuberculosis is not considered gram-positive or gram-negative bacteria. However, the bacterium may weakly stain gram-positive when gram-stained.
What is the full form of AFB?
Brief Description. Acid- Fast Bacilli (AFB) smear and culture are two separate tests always performed together at the MSPHL, Tuberculosis (TB) Unit. AFB smear refers to the microscopic examination of a fluorochrome stain of a clinical specimen.
What diseases are diagnosed using acid-fast procedure?
An acid-fast bacteria (AFB) culture is done to find out if you have tuberculosis (TB) or another mycobacterial infection. Besides TB, the other main mycobacterial infections are leprosy and a TB-like disease that affects people with HIV/AIDS.
What is AFB test for TB?
A sputum stain for Mycobacteria is a laboratory test performed on a sample of your sputum, or phlegm. It’s also known as an acid-fast bacillus (AFB) stain or a tuberculosis (TB) smear. A doctor typically orders the test to determine if a person has tuberculosis (TB) or another type of mycobacterial infection.
What is the meaning of acid-fast?
Acid fastness is a physical property that gives a bacterium the ability to resist decolorization by acids during staining procedures. This means that once the bacterium is stained, it cannot be decolorized using acids routinely used in the process.
