Sometimes a strong antibiotic, and there are none stronger than colloidal silver, can kill off beneficial bacteria and what happens is that harmful bacteria are later able to establish a foothold and dominate. The end result is a yeast type infection. Colloidal silver is deadly on single-celled organisms and most believe that with heavy intake that includes both beneficial and bad gut flora. Just in case, it is a good idea to take probiotics to keep good intestinal flora established.