This is one of those CS claims that have been around forever. I do not believe it. Ode already responded with a much better explanation of why than I can give, so I'm just adding my opinion that he is correct and the statement below is wrong.
sol

At 12:40 AM 2/16/2010, you wrote:
certain BACTERIA ARE ESSENTIAL TO HEALTHY BODY FUNCTION. SEVERAL RESEARCHERS CLAIM COLLOIDAL SILVER ONLY ATTACKS THE UNFRIENDLY PATHOGENS AND WILL LOT HARM THE FRIENDLY, BUT ONE MUST WONDER HOW IT CAN POSSIBLY DIFFERENTIATE. THE EXPLANATION IS THAT THE FRIENDLY BACTERIA ARE AEROBIC, WHILE UNFRIENDLY BACTERIA ARE ANAEROBIC. SILVER DOES NOT ATTACK BACTERIA DIRECTLY, BUT RATHER DECOMPOSES CERTAIN ENZYMES THE ANAEROBIC BACTERIA, VIRUSES, YEAST, AND MOLDS REQUIRE. THE SILVER ACTS AS A CATALYST AND IS LOT CONSUMED IN THE PROCESS. IT IS PROBABLE THAT THIS INDIRECT ACTION IS ALSO THE REASON BACTERIA CANNOT DEVELOP A RESISTANCE TO SILVER, AS THEY DO TO ANTIBIOTICS. FROM DR. CLARKS ARTICLE NEWSLETTER FOR PRACTITIONERS,{ FINDING THE WAY}. Makes sense