James Wesley:
At a slide show about extreme trekking in the tropics, I asked the speaker what they used as a topical antibiotic and antifungal medicine while on the expedition. The speaker said they relied on Gentian Blue, an antibiotic that was used in World War I and II.
Gentian Blue (or Crystal Violet) is used as a clothing dye. The early chemical industry put a big emphasis on the development of dyes. In the race to discover the first antibiotics, every chemical on the shelf was tested, and Gentian Blue was found to have powerful antibacterial, antifungal, and antiparasitical properties.
Gentian Blue is still used to treat bacterial and fungal skin infections and thrush (yeast) infections of the mouth. It might be useful for the treatment of drug resistant Staph infections. It is not used for the treatment of deep wounds because it can permanently tattoo the tissue, but in a survival situation this might not be an issue. It will also indelibly stain cloth, so it should be handled with care. Gentian Blue is considered nontoxic enough for oral use (and it has been used to treat VD). It is not approved for internal use because of possible cancer risks, but if I were suffering from gangrene, I would not let that worry me.
Gentian Blue used to be available on the pharmacy shelf back with the bottles of iodine. 2% Gentian Violet Solution