Ziehl–Neelsen stain

Source: Wikipedia, the free encyclopedia.
Microscopic visualisation of the acid-fast bacteria Mycobacterium tuberculosis (top) and Mycobacterium leprae (bottom) and background cellular material in blue using the Ziehl–Neelsen stain

The Ziehl-Neelsen stain, also known as the acid-fast stain, is a bacteriological staining technique used in cytopathology and microbiology to identify acid-fast bacteria under microscopy, particularly members of the Mycobacterium genus. This staining method was initially introduced by Paul Ehrlich (1854–1915) and subsequently modified by the German bacteriologists Franz Ziehl (1859–1926) and Friedrich Neelsen (1854–1898) during the late 19th century.

The acid-fast staining method, in conjunction with

bronchoalveolar lavage fluid. These acid-fast bacteria possess a waxy lipid-rich outer layer that contains high concentrations of mycolic acid, rendering them resistant to conventional staining techniques like the Gram stain.[1][2]

After the Ziehl-Neelsen staining procedure using carbol fuchsin, acid-fast bacteria are observable as vivid red or pink rods set against a blue or green background, depending on the specific counterstain used, such as methylene blue or malachite green, respectively. Non-acid-fast bacteria and other cellular structures will be colored by the counterstain, allowing for clear differentiation.[3]

Mycobacteria

In anatomic pathology specimens, immunohistochemistry and modifications of Ziehl–Neelsen staining (such as Fite-Faraco staining) have comparable diagnostic utility in identifying Mycobacterium. Both of them are superior to traditional Ziehl–Neelsen stain.[4]

Mycobacterium are slow-growing rod-shaped bacilli that are slightly curved or straight, and are considered to be Gram positive. Some mycobacteria are free-living saprophytes, but many are pathogens that cause disease in animals and humans. Mycobacterium bovis causes tuberculosis in cattle. Since tuberculosis can be spread to humans, milk is pasteurized to kill any of the bacteria.[5] Mycobacterium tuberculosis that causes tuberculosis (TB) in humans is an airborne bacterium that typically infects the human lungs.[6][7] Testing for TB includes blood testing, skin tests, and chest X-rays.[8] 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.[9] It can also be used to stain a few other bacteria, such as Nocardia. The reagents used for Ziehl–Neelsen staining are carbol fuchsin, acid alcohol, and methylene blue. Acid-fast bacilli are bright red after staining.

Fungi

Ziehl–Neelsen staining is a type of narrow spectrum fungal stain. Narrow spectrum fungal stains are selective, and they can help differentiate and identify fungi.

fungi in the genus Russula.[16][17] Some free endospores can be confused with small yeasts, so staining is used to identify the unknown fungi.[18] It is also useful in the identification of some protozoa, namely Cryptosporidium and Isospora. The Ziehl–Neelsen stain can also hinder diagnosis in the case of paragonimiasis
because the eggs in sputum sample for ovum and parasite (O&P) can be dissolved by the stain, and is often used in this clinical setting because signs and symptoms of paragonimiasis closely resemble those of

History

In 1882

Joseph Kinyoun
by using the Ziehl–Neelsen staining technique but removing the heating step from the procedure. This new stain from Kinyoun was named the Kinyoun stain.

Procedure

Basic steps of the Ziehl-Neelsen staining procedure

A typical AFB stain procedure involves dropping the cells in suspension onto a slide, then air drying the liquid and heat fixing the cells.[21]

Summary of acid-fast stain (Ziehl–Neelsen stain)[22]
Application of Reagent Cell colour
Acid fast Non-acid fast
Primary dye Carbol fuchsin Red Red
Decolorizer Acid alcohol Red Colorless
Counter stain Methylene blue/malachite green Red Blue

Studies have shown that an AFB stain without a culture has a poor negative predictive value. An AFB culture should be performed along with an AFB stain; this has a much higher negative predictive value.

Mechanism explanation

Mechanism of acid-fast staining in acid-fast cells and non-acid-fast cell[23][24][25]

The mechanism of action of the Ziehl-Neelsen stain is not completely understood, but it is thought to involve a chemical reaction between the acidic dyes and the cell walls of the bacteria. The acidity of the dyes causes them to bind more strongly to the cell walls of the bacteria than to other cells or tissues. This results in the selective staining of only those cells that have a high density of cell wall material, such as acid-fast bacteria.[26]

The Ziehl-Neelsen stain is a two step staining process. In the first step, the tissue is stained with a basic fuchsin solution, which stains all cells pink. In the second step, the tissue is incubated in an acid alcohol solution, which decolorizes all cells except for acid-fast cells, which retain the color and appeared as red. The mechanisms by which this color is produced are not well understood, but it is thought that the interaction of the basic fuchsin with the cell wall components of bacteria creates a new molecule that is responsible for the color.[27]

Modifications

See also

References

  1. ISBN 978-0-12-397169-2
    , retrieved 2023-07-28
  2. ISBN 978-0-323-04048-8
    , retrieved 2023-07-28
  3. ^ Aryal, Sagar (2022-08-10). "Acid-Fast Stain- Principle, Procedure, Interpretation and Examples". Microbiology Info.com. Retrieved 2023-07-28.
  4. PMID 32915191
    .
  5. ISBN 978-1260211887
    .
  6. ^ "Tuberculosis (TB)- Basic TB Facts". Centers for Disease Control and Prevention. 2019-06-19. Retrieved 2024-03-06.
  7. ^ "Tuberculosis (TB)- How TB Spreads". Centers for Disease Control and Prevention. 2022-05-03. Retrieved 2024-03-06.
  8. ^ "Tuberculosis (TB) - Testing and Diagnosis". Centers for Disease Control and Prevention. 2022-05-03. Retrieved 2024-03-06.
  9. ISBN 0073522538.[page needed
    ]
  10. S2CID 39812297
    .
  11. ^ Haque, A. (2010). Special Stains Use in Fungal Infections. Connection: 187-194
  12. PMID 28934824
    .
  13. ^ "Histoplasmosis | Types of Diseases | Fungal Diseases | CDC". www.cdc.gov. 2020-12-29. Retrieved 2024-03-06.
  14. ^ "Sources of Histoplasmosis | Types of Diseases | Histoplasmosis | Fungal Disease | CDC". www.cdc.gov. 2021-02-19. Retrieved 2024-03-06.
  15. ^ "Symptoms of Histoplasmosis | Types of Diseases | Histoplasmosis | Fungal Disease | CDC". www.cdc.gov. 2021-01-14. Retrieved 2024-03-06.
  16. ISBN 0-934454-87-6.[page needed
    ]
  17. ISBN 0-916422-09-7
    .
  18. PMID 14567744
    .
  19. PMID 26839384
    .
  20. PMID 26655191
    .
  21. ISBN 9781640430327
    .
  22. ^ Acid-Fast Stain- Principle, Procedure, Interpretation and Examples. May 8, 2015 by Sagar Aryal
  23. ^ "Online Microbiology Notes". Online Microbiology Notes. Retrieved 2017-11-29.
  24. ^ "Home – microbeonline". microbeonline.com. Retrieved 2017-11-29.
  25. ^ Kumar, Surinder (2012). Textbook of Microbiology. p. 315.
  26. S2CID 108292027
    .
  27. ^ Sharma, Dr Anubhav (2022-10-01). "Ziehl-Neelsen Stain-Ziehl-Neelsen Staining Method - Microbiology". Witfire. Retrieved 2022-10-03.
  28. PMID 7687254
    .

Bibliography

  • "Microbiology with Diseases by Body System", Robert W. Bauman, 2009, Pearson Education, Inc.

External links
Retrieved from "https://en.wikipedia.org/w/index.php?title=Ziehl–Neelsen_stain&oldid=1220456160"