Some on natural antibiotics below. Can do a search on natural
antibiotic, antifungal, antibacterial properties of garlic, ginger and
licorice as well for more.

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On olive leaf:
http://www.olivetea.com/super_bugs_info.htm

And this one on oil of oregano. (Look at that, even cite some studies?)

http://www.kitchendoctor.com/reprints/wildoregano.html

excerpt:
The antibacterial, antiseptic action of plant oils has been described
in recent
medical literature and may be helpful in fighting biological toxins.
[Journal
Applied Microbiology, Volume 88, 2000] A potent natural antibiotic,
more
powerful than many prescription antibiotics, is oil of OREGANO.

One study showed that oregano completely inhibited the growth of 25
germs such
as Staphylococcus aureas, Escherichia coli, Yersinia enterocolitica and
Pseudomonas aeruginosa. [Journal Food Protection, July 2001]

Oregano has been shown to be effective in eradicating intestinal
parasites in
humans. [Phytotherapy Research, May 2000]

WILD OREGANO, which is quite different than the variety on most kitchen
spice
racks, has over 50 antibacterial compounds. Just one part wild oregano
oil in
4000 dilution sterilizes contaminated water.