The appendix apparently helps here – it’s connected to the gut but unlike most of it which is a straight through pipe is a blind ended tube. Not much of the food (or antibiotics) going through your gut ends up in there so the bacteria there serve as a resevoir for normal gut bacteria which repopulate the gut.
Certainly researchers discovered that if your appendix is removed you are far more likely to get a reoccurance of c-diff.
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