How does ozone kill pathogenic bacteria but not beneficial bacteria, especially with direct contact like drinking ozonated water or rectal insulflation?
There are a couple of things at play here. First of all many pathogenic bacteria are anaerobic and thus cannot tolerate high oxygen concentrations.
Along the same lines, many bacteria cannot tolerate the peroxides formed by the ozone on water and fatty acids.
And finally, a lot of the beneficial effects of ozone come from its ability to stimulate immune function. This in turn leads to destruction of many of the pathogenic bacteria from peroxides and white blood cells.
Although high levels of ozone or peroxides can kill both good and bad bacteria. You will never kill off all the bacteria though so the surviving good bacteria will rebound.