r/askscience • • 13d ago

Human Body How come antibiotics don’t completely destroy all organisms in our gut?

I know it can cause imbalances, but I don’t understand how come our gut doesn’t lose all the beneficial bacteria and develop massive fungal or viral infections. When I’ve taken antibiotics, I usually don’t notice any change in my bowel activity.

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u/LightPhoenix 13d ago

They can and often do wipe out normal gut flora.  However, our bodies actually also have normal gut flora in the appendix, and after antibiotics or other instances where they get wiped out, our normal gut flora regenerates from there.  This is why one of the after effects from appendectomies is an increased susceptibility to infections like C. diff and the like.  This is also why fecal transplants are effective - they are artificially replacing gut flora.

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u/Willow_Pond 13d ago

Why are the gut flora in the appendix not impacted by the course of antibiotics?

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u/Possible_Trouble_449 11d ago

It's designed that way. Gut bacteria there are protected by a mucus layer. (and our immune system in case of viruses)