What is the mordant used in ZN staining?
What is the mordant used in ZN staining?
Unlike the Ziehl–Neelsen stain (Z-N stain), the Kinyoun method of staining does not require heating. In the Ziehl–Neelsen stain, heat acts as a physical mordant while phenol (carbol of carbol fuschin) acts as the chemical mordant.
What is the mordant used in the Ziehl Neelsen acid fast stain procedure?
Franz Ziehl then altered Ehrlich’s staining technique by using carbolic acid as the mordant. Friedrich Neelsen kept Ziehl’s choice of mordant but changed the primary stain to carbol fuchsin.
Which mordant is used in acid fast staining?
Acid-Fast Stains Both use carbolfuchsin as the primary stain. The waxy, acid-fast cells retain the carbolfuchsin even after a decolorizing agent (an acid-alcohol solution) is applied. A secondary counterstain, methylene blue, is then applied, which renders non–acid-fast cells blue.
What is modified Zn stain?
The Modified Ziehl-Neelsen stain (mZN stain) is a type of differential bacteriological stain used to identify acid-fast organisms, mainly Mycobacteria. Acid fast organisms are those which are capable of retaining the primary stain when treated with an acid (fast=holding capacity).
Why ZN staining is called acid fast?
These bacteria can not be stained by simple stains or even by Gram staining. These bacteria can however be stained by drastic measures, and once stained can not be readily decolourized by weak mineral acids. Hence, these bacteria are called acid fast bacilli and the staining method is called acid fast staining.
What is the principle of ZN staining?
This procedure is used to stain mycobacterium tuberculosis and mycobacterium leprae. These bacteria are also called acid fast bacilli. They stain with carbol fuschin, which is a red dye. They retain the dye when treated with acid, which is because of the presence of mycolic acid in their cell wall.
Why is carbol Fuchsin used in acid fast staining?
Carbol fuchsin is used as the primary stain dye to detect acid-fast bacteria because it is more soluble in the cells wall lipids than in the acid alcohol.
What are basic stains?
Basic stains, such as methylene blue, Gram safranin, or Gram crystal violet are useful for staining most bacteria. These stains will readily give up a hydroxide ion or accept a hydrogen ion, which leaves the stain positively charged.
What is the full form of AFB?
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 happens if AFB is positive?
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.
What is Genexpert test?
Introduction: Gene-Xpert, a CBNAAT (catridge based nucleic acid amplification test) is a widely accepted diagnostic test for Tuberculosis. This test is a rapid diagnostic test for Tuberculosis detection as well as Rifampicin resistance in direct smear negative cases.
Which group of bacteria are acid-fast?
Acid-fast bacteria, also known as acid-fast bacilli or simply AFB, is a group of bacteria sharing the characteristic of acid fastness. Acid fastness is a physical property that gives a bacterium the ability to resist decolorization by acids during staining procedures.
Which is Decolorizer used in acid fast staining?
The primary stain used in acid-fast staining, carbol fuchsin, is lipid-soluble and contains phenol, which helps the stain penetrate the cell wall.
What is the color of acid fast bacteria?
The most common staining technique used to identify acid-fast bacteria is the Ziehl–Neelsen stain, in which the acid-fast species are stained bright red and stand out clearly against a blue background.
Is Staphylococcus acid fast?
The small pink bacilli above are Mycobacterium smegmatis, an acid fast bacteria because they retain the primary dye. The darker staining cocci are Staphylococcus epidermidis , a non-acid fast bacterium. This is a combination of a negative stain and a simple stain.
What is the primary stain in acid fast?
The primary stain used in acid-fast staining, carbolfuchsin, is lipid-soluble and contains phenol, which helps the stain penetrate the cell wall. This is further assisted by the addition of heat.
What color does Staphylococcus aureus stain in acid fast?
Lab 4 Gram Staining/Acid Fast Staining
| Question | Answer |
|---|---|
| Staphylococcus aureus cells after the decolorizer is used | purple |
| Moraxella (Branhamella) catarrhalis after the decolorizer is used | no color |
| Bacillus megaterium after the counterstain is added | purple |
| Pseudomonas aeruginosa after the counterstain is added | pink |
What are the steps in acid fast staining?
Acid-Fast Staining Instructions
- Air dry and heat fix a thin film of microorganisms.
- Flood the slide with Carbolfuchsin.
- Flood slide with Acid Alcohol for 30 seconds.
- Counterstain by flooding the slide with Methylene Blue for 30 seconds.
- Dry the slide by putting it between the pages of a book of Bibulous paper.
What diseases can be diagnosed through the 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 are the different staining techniques?
- 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.
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 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 can Mycobacterium be Gram stained?
Mycobacteria contain mycolic acids and have a high GC content in their DNA. A Gram stain cannot penetrate the waxy cell wall. The hydrophobic lipids cause the Gram stain to give no staining or a variable result.
Why are acid fast stains useful?
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 does a positive acid fast stain mean?
A positive result means that bacteria were found and that you may have an infection. The smear is treated with a special acid-fast stain that can provide a preliminary test result in 24 hours.
Where is Mycobacterium tuberculosis commonly found?
Tuberculosis (TB) is an acute or chronic bacterial infection found most commonly in the lungs.
What is the correct order of staining reagents in Gram staining?
The stains are applied to a smear of bacteria on a microscope slide in the following order: crystal violet, Gram’s iodine, decolorizing agent, and safranin.
What does Mycobacterium tuberculosis look like?
The purple rod-shaped organism is a TB bacterium. This name, meaning ‘fungus-bacteria’ refers to shape of the bacillus when it grows in a laboratory: when seen through a microscope it forms heaps of small rods with protective layers around them, and thus looks like a fungus.
What does Mycobacterium leprae look like?
M. leprae is a strongly acid-fast, rod-shaped bacterium. It has parallel sides and rounded ends, measuring 1-8 microns in length and 0.2-0.5 micron in diameter, and closely resembles the tubercle bacillus.
What is the life cycle of tuberculosis?
TB infection happens in 4 stages: the initial macrophage response, the growth stage, the immune control stage, and the lung cavitation stage. These four stages happen over roughly one month.