What is the Difference Between Ziehl Neelsen and Kinyoun Method

Have you ever heard of acid-fast staining? Acid-fast staining is a crucial technique for differentiating bacteria with acid-fastness from those without. This distinctive property allows certain bacteria to resist decolorization by acid and alcohol solutions due to their wax-like, impermeable cell walls. This resistance enables quick and reliable detection of infections caused by acid-fast bacteria, such as tuberculosis, caused by Mycobacterium tuberculosis. The Ziehl Neelsen and Kinyoun are two primary methods used for acid-fast bacilli staining. While both methods serve the same purpose, they differ in their approach.

What is the key difference between Ziehl Neelsen and Kinyoun method? In the Ziehl-Neelsen method, heat acts as a physical mordant to enhance staining, whereas the Kinyoun method achieves staining without the need for heating.

CONTENTS

1. Overview and Key Difference
2. What is Ziehl Neelsen Method
3. What is Kinyoun Method
4. Similarities – Ziehl Neelsen and Kinyoun Method
5. Ziehl Neelsen vs. Kinyoun Method in Tabular Form
6. FAQ – Ziehl Neelsen and Kinyoun Method
7. Summary – Ziehl Neelsen vs. Kinyoun Method

What is Ziehl Neelsen Method?

The Ziehl-Neelsen method is a staining technique initially introduced by Paul Ehrlich and subsequently modified by German bacteriologists Franz Ziehl and Friedrich Neelsen. This method is a two-step staining process. In the first step, the tissue is stained with a carbol fuchsin solution, which stains all cells in pink colour. In the second step, the tissue is incubated with an acid alcohol solution. This decolorizes all cells except for acid-fast cells of bacteria such as Mycobacterium, which retain their color and appear red.

What is Kinyoun Method?

The Kinyoun method is a modified version of Ziehl Neelsen, discovered by Joseph J. Kinyoun. Since it does not use heating like Ziehl Neelsen, the Kinyoun method is also known as the cold method. Kinyoun’s method uses a high concentration of phenol-containing solution, such as basic fuchsin, as the primary stain.

Kinyoun method involves the application of a primary stain like basic fuchsin, a decolorizer like acid-alcohol, and a counterstain like methylene blue.  However, unlike the Ziehl–Neelsen stain, the Kinyoun method of staining does not require heating and uses only a chemical mordant.

What are the Similarities Between Ziehl Neelsen and Kinyoun Method?

1. Ziehl Neelsen and Kinyoun methods are two staining techniques to detect acid-fast bacteria such as Mycobacterium.
2. Both methods use a primary stain, a decolorizer like acid-alcohol, and a counterstain like methylene blue.
3. They are extremely important microbiological techniques.

What is the Difference Between Ziehl Neelsen and Kinyoun Method?

Type of Staining

• Ziehl Neelsen is a staining technique that requires a gentle heating of the bacterial smear.
• The Kinyoun method is a staining technique for bacterial species that does not require heating of the smear.

Discovery

• Ziehl Neelsen was initially introduced by Paul Ehrlich and subsequently modified by German bacteriologists Franz Ziehl and Friedrich Neelsen.
• On the other hand, the Kinyoun method was introduced by Joseph J. Kinyoun.

Safety

• Ziehl Neelsen’s method might cause safety issues since it involves heating.
• The Kinyoun method is safer since the phenol is not heated during the procedure.

The infographic below presents the differences between Ziehl Neelsen and Kinyoun method in tabular form for side-by-side comparison.

FAQ: Ziehl Neelsen and Kinyoun Method

1. What color is acid-fast positive?

• Red color cells indicate the presence of acid-fast bacteria.

2. What is the principle of AFB?

• In acid-fast bacteria, the cell wall is resistant to decolorization with acid alcohol. Hence, when decolorizing, acid-fast bacteria will not be decolorized. Primary stains will be retained in their cells. Therefore, they appear in red color while non-acid fast bacteria counter stain with blue/green color.

3. What is used in the Ziehl-Neelsen staining technique that is not used in the Kinyoun staining technique?

• In the Ziehl-Neelsen staining technique, heat is used as a physical mordant, while it is not used in the Kinyoun staining technique.

Summary – Ziehl Neelsen vs Kinyoun Method

Ziehl Neelsen and Kinyoun method are two staining techniques to detect acid-fast bacteria such as Mycobacterium. Ziehl Neelsen method uses carbol fuchsin as the primary stain. Kinyoun’s method uses basic fuchsin as the primary stain. Furthermore, in the Ziehl-Neelsen method, heating is used as the physical mordant, whereas in the Kinyoun method, heating is not involved. Acid-fast bacteria appear in red at the end of the staining, while non-acid-fast bacteria stain in blue color.  This summarizes the difference between Ziehl Neelsen and Kinyoun method.

Reference:

1. “Ziehl-Neelsen Stain – An Overview.”  ScienceDirect Topics.
2. “Dalynn Biologicals.”  Kinyoun Carbol Fuchsin Stain.

Image Courtesy:

1. “Ziehl-Neelsen stain Nigative for acid fast bacilli (AFB _ve)” By Albaraa Mehdar (CC BY-NC 2.0 DEED) via Flickr

2. “Kinyoun Stain, organism Mycobacterium smegmatis” By Kevy234 – Own work (CC BY-SA 4.0) via Commons Wikimedia