Silver(Ag) particles have been used as an antibiotic for a long time but fell into disuse with modern antibiotics (how can one patent silver(Ag)!).
“biochemical responses to the toxicity of Ag were very different in different bacteria, indicating the complex toxic mechanism of Ag nanoparticles (NPs). Ag NPs are toxic to a great variety of organisms, including bacteria, fungi, algae, protozoa etc.,” 
I spotted an interesting article
“The use of silver in medicine dates back thousands of years, and scientists have long known that the metal is a potent antibacterial agent. Silver ions perform their deadly work by punching holes in bacterial membranes and wreaking havoc once inside. They bind to essential cell components like DNA, preventing the bacteria from performing even their most basic functions…Reservoirs of silver nanoparticles had built up in their corpses, indicating that the dead bacteria act like sponges, soaking up silver as they die. The stored silver can leach out to the environment, “especially if the environment contains other sponges for that silver,” says chemist David Avnir of the Hebrew University of Jerusalem” [ScienceMag] May, 2015.
So what would happen in the gut? Are certain families of bacteria more prone to absorbing/being killed by the silver OR is silver a “nuclear bomb” that kills the entire population?
- E. Coli appears resistant, killed E. hirae 
- Killed Enterococcus within 3 hrs, Killed Citrobacter in 6 hrs 
- The longer kill time means that the silver could be cleared before Citrobacter is eliminated.
- Gram Negative bacteria tolerates, d Variovorax paradoxus tolerates 
- Resistant: Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, Staphylococcus aureus …there is an association of antibiotic resistance with metal resistance 
- Resistant Enterobacteriaceae 
- Effective Streptococcus 
- Effective Bifidobacterium 
- Effective Lactobacillus 
I took the above and added it to my post on matrix of bacteria shifts seen in CFS and it came out as a -2, not a good match for CFS.