This is all true. We aren't immune to all their effects long term, though. The mouth is the best example. Bacteria will release all sorts of compounds as they h

This is all true. We aren't immune to all their effects long term, though. The mouth is the best example. Bacteria will release all sorts of compounds as they have to eat. The enamel is able to resist (and reform) but it needs help if you have any hope of maintaining all your teeth past your prime reproductive age.