Ziehl-Neelsen stain

Mycobacterium tuberculosis visualization using the Ziehl-Neelsen stain.

The Ziehl-Neelsen stain, also known as the acid-fast stain, was first described by two German doctors; Franz Ziehl (1859 to 1926), a bacteriologist and Friedrich Neelsen (1854 to 1894), a pathologist. It is a special bacteriological stain used to identify acid-fast organisms, mainly Mycobacteria. Mycobacterium tuberculosis is the most important of this group, as it is responsible for the disease called tuberculosis (TB)along with some others of this genus. It is helpful in diagnosing Mycobacterium tuberculosis since its lipid rich cell wall makes it resistant to Gram stain. It can also be used to stain few other bacteria like Nocardia. The reagents used are Ziehl-Neelsen carbolfuchsin, acid alcohol and methylene blue. Acid fast bacilli will be bright red after staining.

Procedure

• 1. Cover with tissue paper
• 2. Flood slide with carbolfuchsin, the primary stain, for 2 minutes while heating with steam.
• 3. Remove paper cover, decolorize slide with a mixture of hydrochloric acid and ethanol.
• 4. Counter stain with methylene blue.

Modifications

• 5% Sulphuric Acid is used for staining Mycobacterium leprae instead of the 20% used for Mycobacterium tuberculosis
• Kinyoun modification (or cold Ziehl-Neelsen technique) is also available.

References

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

Online protocol examples

• Ziehl-Neelsen protocol (PDF format).

See also

• Lowenstein-Jensen medium

External links

• Media related to Category:Ziehl-Neelsen stain at Wikimedia Commons