We inherit some anti-bodies from our mother, but eventually have to learn to make our own. We aren't doing our kids any favors raising them in sanitized environments. Let 'em eat some dirt.
The only time I've needed an antibiotic is when I've had to have surgery with a lengthy hospital stay. I've had manure covered wounds, punctures, lacerations, tore off nails, animal bites, and even had a Lamma spit in my mouth once. Not one of those times did I get an infection. Yet one three hour surgery with a hospital stay and I end up having to have the entire pharmacy in drip bags for weeks.