I understand all of this; what i meant to ask, i think, is: How do these detrimental gut flora get in to our systems, and how do we prevent that, or get rid of

I understand all of this; what i meant to ask, i think, is: How do these detrimental gut flora get in to our systems, and how do we prevent that, or get rid of them? Is taking more bacteria helpful, in that it can out-compete the fungus? My experience with lacto and yeast is that both of those are well-equipped to outcompete nearly everything, especially if you give them lots of pure sugar.