Bacteria are amazingly adaptive, but nothing shows the absolute persistence of life like the radiotrophic fungus found in the reactor at Chernobyl. This fungus actually uses melanin to produce energy for the organism. It isn’t just surviving radiation, it is feeding off of it.

The original poster does not seem to understand how ephemeral the boundary between organisms and their biome is in practice. The colony of bacteria is equally unaffected as the macro organism is to the death of individual cells destroyed by alcohol. If you don’t brush and floss, but do use mouthwash you will have major problems with gum disease. Less then someone who does nothing but still severe enough to reduce your life expectancy.

More to the point if you did kill all the bacteria in your body you would die from malnutrition if nothing else.