Staining Result of Mycobacterium Tuberculosis with Gram Stain
Mycobacterium tuberculosis, the bacteria responsible for tuberculosis, is acid-fast, meaning it resists decolorization with acid-alcohol during the Gram staining procedure. This is due to the presence of a waxy, hydrophobic layer in its cell wall, primarily composed of mycolic acid.
How Gram Staining Works
The Gram staining technique is a differential staining method that differentiates bacteria into two groups: Gram-positive and Gram-negative. This is based on the differences in the bacterial cell wall structure.
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Gram-positive bacteria have a thick peptidoglycan layer in their cell wall that retains the primary stain, crystal violet. This results in the bacteria appearing purple under a microscope.
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Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane that does not retain the crystal violet stain. After decolorization with alcohol, they are counterstained with safranin, appearing pink under the microscope.
Why Mycobacterium Tuberculosis is Acid-Fast
Mycobacterium tuberculosis's thick, waxy cell wall prevents the entry of crystal violet stain and also resists decolorization with alcohol. This is why it is considered acid-fast.
Staining Mycobacterium Tuberculosis
Instead of the Gram staining procedure, acid-fast staining is used to identify Mycobacterium tuberculosis. This involves using a strong dye like carbolfuchsin, which penetrates the waxy layer. Following decolorization with acid-alcohol, the bacteria retain the red color, allowing them to be differentiated from other bacteria.
Conclusion
Therefore, Mycobacterium tuberculosis will not stain properly with the Gram staining method. It will appear colorless as it does not retain the crystal violet stain. Acid-fast staining is the appropriate method for identifying Mycobacterium tuberculosis, resulting in a characteristic red color under the microscope.
