Thanks for taking the time to respond. As you point out some very interesting information, it doesn't really help to scientifically conclude what effect H2O2 (Hydrogen-Peroxid) would have on gut flora.
I guess there is no real easy answer to my question. It would seem that the trick, as you pointed out, is to not disrupt the microbiome in the first place. Sadly, once it gets out of balance, the trick of replacing it is quite the dicey one.