I read somewhere that if you get yeast (presumably wild yeast) in your stomach, they can ferment, (if not killed by stomach acid), and that can be particularly uncomfortable.
Under ordinary gastrointestinal conditions, why would the stomach acid not kill all these microbes (molds, bacteria, virii, etc)?
If not killed, all these microbes presumably multiply. So why are yeasts so much more uncomfortable for you than molds etc?