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Chronic Granulomatous?

Discussion in 'Step I' started by boardssuck, Jun 17, 2008.

  1. boardssuck

    boardssuck 2+ Year Member

    Jun 8, 2008
    So CGD lacks NADPH oxidase so it can't make radical O2 --> no H2o2 --> no hypochlorite....

    And they are most commonly infected by catalase positive bugs which can degrade H202...but why is CGD mostly infected by catalase positive if the the person can't make H202 in the first place?
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  3. medstylee

    medstylee 1K Member 10+ Year Member

    Oct 15, 2003
    the bacteria produce their own endogenous H2O2.
  4. SeventhSon

    SeventhSon SIMMER DOWN 7+ Year Member

    Aug 23, 2005
    San Diego
    there are also probably minor pathways that generate H2O2 aside from NADPH oxidase, and the bugs can degrade this small amount... with functioning NADPH oxidase you can easily overwhelm their capacity.
  5. tfom08

    tfom08 2+ Year Member

    May 2, 2008
    Say CGD guy gets infected with strep, the strep makes H2O2 and then the guy's neutrophils turn that H2O2 into hypochlorite because his myeloperoxidase works. But if guy gets infected with staph, the H2O2 produced by the bacteria gets broken down by the staph catalase before it can be converted to hypochlorite, so there is not a sufficient response to kill the bugs.
  6. 45408

    45408 aw buddy 7+ Year Member

    Jun 13, 2004
    Because you're misunderstanding it. They still have H2O2, they just don't have the free radicals. The hydrogen peroxide still kills most bugs, but catalase positive bugs simply degrade the hydrogen peroxide. Free radicals kill everything.
  7. It'sElectric

    It'sElectric 10+ Year Member

    Dec 5, 2005
    I'm not a genius in regards to any of this stuff, but I think you're a little off. I think tfom had it correct. A person w/ CGD doesn't have H2O2, because they're unable to make it, since they lake the superoxide free radical made during the respiratory burst. As tfom said, the bacteria bring with them their own endogenous H2O2 and the catalase positive bugs are able to destroy it before it can complex with myeloperoxidase to form bleach. The catalase negative bugs, however, cannot destroy their own H2O2, so it complexes with the MPO (still in a person with CGD) to form bleach, which kills the bug.

    I probably didn't type that up very clearly, but I tried. Read tfom's....he had it right to begin with, or at least I think so.
  8. Monica Lewinsky

    Monica Lewinsky 2+ Year Member

    Jan 18, 2008

    You pretty much said exactly what Goljan says in his audio. Lecture 3 or 4 I believe.
  9. osli

    osli Senior Member 5+ Year Member

    Oct 13, 2005
    Yeah... what TheProwler describes is myeloperoxidase deficiency, which does exist but is usually asymptomatic and goes undetected. Most healthy people compensate well enough. I think it the genetics are wacky - not likely to be asked anyway.
  10. 45408

    45408 aw buddy 7+ Year Member

    Jun 13, 2004
    oh wail. I can never seem to explain things on SDN.

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