Why is Mycobacterium tuberculosis stained by Ziehl-neelsen?
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Why is Mycobacterium tuberculosis stained by Ziehl-neelsen?
When looking at the smears for TB, it is stained using an acid-fast stain. These acid-fast organisms like Mycobacterium contain large amounts of lipid substances within their cell walls called mycolic acids. These acids resist staining by ordinary methods such as a Gram stain.
What is the reason for the acid fastness of Mycobacterium tuberculosis?
The acid-fastness of Mycobacteria is due to the high mycolic acid content of their cell walls, which is responsible for the staining pattern of poor absorption followed by high retention.
What is the purpose of Ziehl-neelsen?
PURPOSE: Used in the demonstration of acid-fast bacteria belonging to the genus ‘mycobacterium’, which include the causative agent for tuberculosis. PRINCIPLE: The lipoid capsule of the acid-fast organism takes up carbol- fuchsin and resists decolorization with a dilute acid rinse.
Which staining is performed on TB bacilli?
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 primary stain in the Ziehl Neelsen acid-fast stain procedure?
- Primary Stain: 0.3% Carbol-fuchsin. Dissolve 50 g phenol in 100 mL ethanol (95%) or methanol (95%).
- Acid fast: Bright red to intensive purple, Red, straight or slightly curved rods, occurring singly or in small groups, may appear beaded.
- Acid-fast: Mycobacterium tuberculosis, Mycobacterium smegmatis.
Why is Ziehl neelsen method called hot method?
The Ziehl-Neelsen method of staining is also called the hot method as it involves heating the carbolfuchsin stain. In contrast, the historic method of staining called the Kinyoun method does not involve heating and is hence known as the cold method. Currently, the cold method is already obsolete.
What is the expected result from an acid-fast stain of sputum from a tuberculosis patient?
Sputum, or phlegm, is often used to test for Mycobacterium tuberculosis, to find out if a patient has TB. This bacterium is completely acid-fast, which means the entire cell holds onto the dye. A positive test result from the acid-fast stain confirms the patient has TB.
What is the purpose of acid-fast staining?
How do you identify Mycobacterium tuberculosis?
The Mantoux tuberculin skin test (TST) or the TB blood test can be used to test for M. tuberculosis infection. Additional tests are required to confirm TB disease. The Mantoux tuberculin skin test is performed by injecting a small amount of fluid called tuberculin into the skin in the lower part of the arm.
What is the result of acid-fast staining?
A positive test result from the acid-fast stain confirms the patient has TB. In other types of acid-fast bacteria such as Nocardia, only certain parts of each cell retain the dye, such as the wall of the cell. A positive test result from a partial or modified acid-fast stain identifies these types of infections.
What color would bacterial cells appear if the patient has tuberculosis?
Under the microscope, the bacillus is seen as a bright red rod, while the surface that it grows on is colored blue. All bacteria that react in this way to a Ziehl-Neelsen stain are called acid-fast bacteria. The staining technique is used for the diagnosis of TB infection.
What bacteria causes AFB?
Bacteria displaying acid fastness include:
- Genus Mycobacterium – M. leprae, M. tuberculosis, M. smegmatis, M. Avium complex, M. kansasii.
- Genus Nocardia – N. brasiliensis, N. cyriacigeorgica, N. farcinica, and N. nova.
