Silver Boosts Antibiotic Efficacy

When Collins and his colleagues supplemented antibiotics with a small amount of silver, both in vitro and in a mouse model of a urinary tract infection, the combination killed up to 1,000 times more bacteria than the antibiotics did on their own. In addition, the researchers showed that silver sensitizes Gram-negative bacteria to vancomycin, a large-molecule antibiotic that usually can’t breach the outer coating on the bacterial cell membranes.

“This work shows that silver can be used to enhance the action of existing antibiotics against Gram-negative bacteria, thus strengthening the antibiotic arsenal for fighting bacterial infections,” the authors wrote.

Vance Fowler, an infectious disease physiologist at Duke University in North Carolina, told Nature that the study is “really cool” but warned that silver can be toxic. But Collins said that even with non-toxic doses of silver, his team observed enhanced antibiotic efficacy in mouse models of infection. Collins added that other researchers might now attempt to find non-toxic compounds that mimic silver’s bacteria-weakening mechanisms.