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Gram negative bacteria and antibiotics?

  1. Jan 19, 2004 #1
    A high level of peptidoglycan (polysaccharide) in the cell wall of bacteria will be stain gram positive (purple). Cells with a lower concentration of peptidoglycan in the cell walls are gram negative (pink).

    Gram negative cells have an outer membrane that is toxic to mammalian physiology and helps protect cells from antibiotics.

    How does having a lesser concentration of the polysaccharide in the cell walls (gram negative) give it more resistance to antibiotics? Is it because a thinner cell wall will give less protection against mutagens so the cell is more likely to survive the antibiotics?
  2. jcsd
  3. Jan 19, 2004 #2


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    This is not the difference between gram positive and gram negative. the peptidoglycan in gram positive is directly expose to the environment whereas the peptidoglycan is gram negative is covered by the outer membrane. The outer membrane will not allow the purple stain to come in before the acohol wash.

    As you said it is the outer membrane that give a better protection against the antibiotics that target cell wall. The OM block the action of the antibiotic by making the cell wall less available to the substrate.
  4. May 13, 2009 #3
    yes , what he said was right .i also thinkthat even if low amounts of dye did penetrate OM ,it wud b pulled by dehydating acid alcohol . here cud u tell me wat is function of iodine ?
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