Micro Lab 9

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Micro Lab 9
2011-07-24 14:40:21
micro lab

micro lab 9 study guide
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  1. Describe how to perform the Kinyoun (cold method) acid-fast staining procedure, step by step, and the purpose of each reagent used.
    • Transfer stock culture to slide, air dry, heat fix
    • Place slide on rack and flood with carbofusion for 5 min, rinse with water & drip decolorizer on slide to rinse until there is just a tint of color running off.
    • Rinse with water place on rack and flood with brilliant green for 2 min.
    • Rinse with water, blot dry, and observe under microscope
    • Primary: carbofusion is retained by acid fast waxy complex in cell wall.
    • Decolorizer: removes primary from non-acid fast bacteria
    • Counter stain: stains the non-acid fast bacteria blue green or green
  2. What is the major difference between the Zieh-Neelson and the Kinyoun acid-fast stain procedure? What is in the Kinyoun carbofuschsin that is not in the Zieh-Neelsen's and what does it do?
    • Zieh-Neelson uses heat to penetrate cell wall with carbofusion
    • Kinyoun- Uses a wetting agent instead of heat to get the stain into the cell wall with its high lipid content
    • Carbofusion in Kinyoun had torbitity 7 or 4 as a wetting agent
  3. Why are some organisms acid-fast and list 3 organisms that are?
    • High lipid in the cell wall.
    • 3 organisms: Microbacterium, norcardia, cryptosporidium
  4. Can Gram positive or Gram negative organisms be acid-fast?
    No, because these bacteria do not contain the high lipid content in the cell wall that is necessary to retain the acid-fast stain upon decolorization