I just read a similiar article myself about garlic being studied and how it did not kill any of the good bacteria, only bad, that oregano killed a few of the good bacteria even-- though not many. And how Antibiotics actually kill almost all good and very few bad and make fungi actually worse.
I found a site that tells how to make your own collidal silver, perhaps that would keep you from getting contaminated collidal...here is the url---http://www.fasterhorses.com/collsilvermaker.html