Anaerobic is another criteria for Miracle-Mineral-Supplement target of destruction. L. acidophilus can survive nicely in an oxygen environment. Others can too. L. acidophilus also has a pH slightly higher than 2. It is likely that they have to be low pH as well as anaerobic. They also have to be electron donors. Somehow we need to find out how to determine if the pathogen meets all these requirements. I suspect that the cells of our body tissue do not meet ALL these requirements and are therefor safe.
That is also to say that some bad pathogens may be safe as well.