Yeasts and molds in the stomach

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?

[homebrews]

If I'm not mistaken...I don't 'believe' yeast can survive...at least not the brewers yeast or baker's yeast we're accustomed to consuming (saccharomyces)...

[bsmsl]

Usually problems with yeast arise after antibiotic use.  Yeast doesn't live in the stomach, but in the digestive track.  The most common one being candida.  Digestive bacteria keep yeast populations down.  Antibiotics kill all bacteria in your system, even the beneficial, digestive bacteria allowing for an overgrowth of the yeast (yest infections of various sorts).  For this reason it is recommended that you eat a lot of live culture yogurt when taking an antibiotic.  In some cases, probiotics are needed to replenish the necessary, digestive bacteria.

I hope that helps you some.

[MrBurps]

Homebrews (and bsmsl), thanks for taking the time to respond.