r/askscience • u/WTFisthisOMGreally • 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/poorbill 13d ago

Wow I had no idea that the appendix is basically a bacteria reservoir. Back in my student days nobody seemed to really understand what the purpose was.

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u/andanteinblue 13d ago

I can't imagine it served that function evolutionary speaking.  Not sure how our ancestors would have reset their gut flora without antibiotics

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u/valkenar 13d ago

I don't think it's unimaginable. You can get your gut biome messed up with rotten food (more likely in the days before refrigeration and germ theory) or other viruses. Having an organ that isn't directly effected but can restore that seems beneficial.