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Dangerous bacteria

  1. Jan 16, 2015 #1
    It is known that some bacteria are dangerous ONLY when they're in the wrong place, f.i. E. Coli. Does anyone know some more examples?
     
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  3. Jan 16, 2015 #2

    SteamKing

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    Just about any bacterium can pose a potential health hazard if it is in the 'wrong place', which is a rather vague term.
     
  4. Jan 16, 2015 #3
    E. Coli's natural habitat inside the body is the lower intestine. That's his place, because outside it, he can be harmful. So it's not a harmful bacterium in defenition, only when it resides at the wrong place.

    I meant if there are any examples of other bacteria, who's natural habitat is f.i. the liver, and outside it, it can be harmful. Does anyone know such an example?
     
  5. Jan 16, 2015 #4

    berkeman

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    What is the context of your question? Is this for schoolwork? Can you tell us some of the examples that you have found so far in your studies? :-)
     
  6. Jan 16, 2015 #5

    Ygggdrasil

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    It's useful to think of humans as a sort of misshapen, hollow cylinder where the outside surface of the cylinder is our skin, the inside surface is our digestive tract, and the stuff in between is our internal organs. If you think of us this way, you'll see that our digestive tract is topologically part of our outside, and is a place where things in our environment interface with us, just like our skin. This is one reason why it's not troublesome to have bacteria and other microbes living in our gut; our body treats it as if it's part of the outside world and maintains barriers to protect itself from these microbes. Because our body keeps bacteria away from our true insides, you won't find any bacteria whose natural habitat is say, the liver or any other internal organ.
     
  7. Jan 19, 2015 #6
    Are you sure? Prevotella, Sphingomonas, Streptococcus are bacteria that belong to our lungs. Bacteroides pneumosintes belong to our pharynx, Acinetobacter calcoaceticus and Acidaminococcus fermentans to our large intestines, Bacterionema matruchotii to our gingiva, Citrobacter freundii to our sputum, the list goes on and on. They are not dangerous in their own area, but my question is if some of them are, just like E. Coli, dangerous outside their own area, and instead, inside an other one.
     
  8. Jan 19, 2015 #7
    The idea in Ygggdrasil's post, although not explicit in the matter, covers the respiratory tract as well. As we are constantly breathing, all tissues and organs involved with respiration are interacting with the outside world constantly. It only makes sense that some bugs would find themselves a nice home at different sites which are still "part of the outside" so to speak. Compare, for example, the difficulty of a bug getting into our lungs versus a bug getting into, say, the liver or the brain. Or compare the microorganisms found in our intestines with those found in the peritoneal cavity.
     
  9. Jan 20, 2015 #8

    NascentOxygen

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    I think you'll find that the dangerous E. coli is a rare mutant strain that wreaks havoc if it takes hold. Ordinary old E. coli is comparatively harmless. (I base this on a discussion with my microbiology lab instructor, and recall her saying she would happily drink a glass of E. coli. We also discussed how she would start the culture, but I'll spare you the details of that.)

    A couple of years back some people died from E. coli that they ingested, it came from the skin of rock melons. When the melon was sliced the knife pushed bacteria from the skin into the flesh. How did E. coli get onto the skins of melons? From fertiliser ---- animal manure spread around the fields where the melons were grown. (Though they never did specify which animals.... )

    Staphylococcus is another resident bacteria (found on our skin and in our nose and throat) which if it gets out of control can cause skin infections (boils).
     
  10. Jan 20, 2015 #9

    Ygggdrasil

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    Yes, there will certainly be examples of native microflora in some regions (for example, the gut) causing disease if they colonize a different area (like the nasal cavity or urinary tract). My point was just that many internal organs (like the liver) will not have bacteria in their native environments.
     
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