Albert Staining- Principle, Reagents, Procedure, Results, Interpretation


The objective of this article is to explain the principle, reagents, procedure, results, and interpretation of Albert staining, a differential staining technique used to stain and observe metachromatic granules from a Corynebacterium diphtheriae culture.

Corynebacterium diphtheriae is a Gram-positive, non-spore-forming, club-shaped bacterium that causes diphtheria, a serious respiratory infection that can lead to suffocation and death. One of the distinctive features of this bacterium is the presence of metachromatic granules in its cytoplasm. These granules are composed of polyphosphate and serve as energy reserves for the bacterium. They are called metachromatic because they change color when stained with certain dyes.

Albert staining is a simple and rapid method to detect these granules and differentiate Corynebacterium diphtheriae from other similar bacteria that lack them. It involves two staining solutions: Albert solution 1, which contains toluidine blue and malachite green as the primary stains, and Albert solution 2, which contains iodine and potassium iodide as the mordant. The mordant enhances the binding of the primary stains to the granules and makes them more visible under the microscope.

By using Albert staining, one can observe that the metachromatic granules appear as bluish-black dots at the poles or along the sides of the green-stained bacilli. This contrast helps to identify Corynebacterium diphtheriae and confirm its diagnosis.

In this article, we will describe how to prepare the Albert staining solutions, how to perform the staining procedure, how to interpret the results, and what are the applications and limitations of this technique. We hope that this article will be useful for students, researchers, and health professionals who are interested in learning more about Albert staining and Corynebacterium diphtheriae.