List the result obtained (acid-fast/non-acid-fast) from the preparations of each

Question

List the result obtained (acid-fast/non-acid-fast) from the preparations of each of the assigned organism. Normally when viewing a stained preparation. One bases decisions on the predominant form in the field. Why is this not the procedure when viewing an acid-fast preparation? List 2 condition(s) when an acid-fast organism may appear non-acid-fast. Why do Mycobacterium organisms tend to occur in groups or clumps on a preparation? Considering the nature of the cell wall of Mycobaterium organisms, how might you expected them to react to gram staining? What diseases are diagnosed using the acid-fast procedure? Have you encountered these diseases? If yes, in what setting?

Explanation / Answer

Answer:

1)Staining is technique used in microscopy to enhance contrast in the microscopic image,Stains and dyes are frequently used in biological tissues for viewing, often with the aid of different microscopes. Microscopes are of little use unless the specimens for viewing are prepared properly. Microorganisms must be fixed & stained to increase visibility, A stain is a substance that adheres to a cell, giving the cell color. The presence of color gives the cells significant contrast so they are much more visible.Acid Fast staining technique or Ziehl Neelsen stain divides bacteria into acid fast and non-acid-fast.In this type some bacteria resist decolourization by both acid and alcohol and hence they are referred as acidfast organisms.

2)In acid fast reactions conditions:

1)Acid-fast organisms are highly resistant to disinfectants and dry conditions.

2)Acid-fast organisms are characterized by wax-like, nearly impermeable cell walls; they contain mycolic acid and large amounts of fatty acids, waxes, and complex lipids

3)To produce cords like strands of bacili .there may be some indication of which species is present based on characteristic cording but this is highly subjective and not recommended as a routine method of determining species).

4)Due to high amounts of lipids in their cell walls, mycobacteria cannot be stained with Gram stain and remain colorless. In the acid-fast staining procedure, mycobacteria are first stained with the red dye basic fuchsin and the cells are then decolorized and re-stained with methylene blue. Basic fuchsin binds to lipids in the cell wall and turns mycobacteria red while other bacteria stain blue.

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