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Do Antibiotics kill good bacteria too?

  1. Oct 8, 2013 #1
    Good bacteria are a normal part of the flora that live in the intestines and are necessary for healthy living and good digestion.
    Recently I had a urinary tract infection caused by a bacteria, and the doctor prescribed a strong antibiotic, Cipro, for seven days.
    It worked and the infection is gone, but does Cipro also kill the good bacteria in my intestine?
    If it does kill them, do they return when I eat a normal diet?
  2. jcsd
  3. Oct 8, 2013 #2


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    Antibiotics kill specific populations - for example consider the antibiotics which are effective/ineffective with gram negative bacteria (see http://en.wikipedia.org/wiki/Gram-negative_bacteria#Medical_treatment).

    Once when I was treated for a strep throat I managed to get a C.Dif. infection - now whenever I take antibiotics I take eat live culture yogurt or take acidopholus pills.

    Another way is to reinfect your intestines with the previous population; it is now believed that the vermiform appendix acts as such a reservoir (but mine was removed when I was a child). Another solution is described here: http://abcnews.go.com/Health/wireStory/pills-made-poop-cure-gut-infections-20457325
  4. Oct 8, 2013 #3


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    I'm not sure if Cipro destroys the flora in the gut that keeps C. Diff in check, but as UltrafastPED experienced, my mother had a similar experience where she was placed on a strong antibiotic treatment post-op, and as a result, she developed a life-threatening C. Diff infection. We waited for about 48 hrs to see if she was going to live, and she survived, but at a toll to her health.
  5. Oct 9, 2013 #4


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    Yes, strong antibiotics kill all bacteria, unless the bacteria have grown resistant. That's why, when you take a strong course of oral antibiotics, one of the side effects is increased diarrhea. All of your gut bacteria have been wiped out, preventing the normal formation of stool. The gut bacteria will return in time, after you have stopped taking the antibiotics, and there are supplements you can take (acidophilus) to speed replacement of these organisms in your gut.
  6. Oct 9, 2013 #5


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    Short version:



    Different people react differently. I don't react at all to a typical antibiotic therapy (in terms of side effects), I know someone for whom each therapy means a sure fungal infection (so they take antibiotic combined with antifungal agent, plus a lot of probiotics - but even that doesn't guarantee lack of infection).
  7. Oct 9, 2013 #6

    jim mcnamara

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    Strong antibiotics kill virtually all of the the bacteria that are susceptible. Good and bad. The subsequent effects vary. Killing everything in your gut would have very serious effects. Cipro will not do that. It may give bad bacteria a chance to take over and make you ill.

    A good strategy is to consume live Lactobacillus containing dairy items like yogurt.

    There are only so many places in your gut where certain bacteria can grow well. Think of available housing.
    If too many bacteria die off, free housing becomes available to invasive pathogenic microflora. Eating yogurt with live cultures takes up a lot of available housing.

    Clostridium difficile is one of the problem bacteria. http://en.wikipedia.org/wiki/Clostridium_difficile
  8. Oct 9, 2013 #7

    There are now tests for C difficile which can detect the toxin and the antigen. They are currently recommended for hospitalized patients who already have diarrhea. While C difficile is not part of the normal flora, the infection can be limited by a healthy normal flora and so remain asymptomatic.

    http://www.mc.vanderbilt.edu/documents/infectioncontrol/files/Guidance for Providers FINAL 2011.pdf

    There is currently a recommendation to establish screening programs in hospitals for C difficile.

    Last edited: Oct 9, 2013
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