A scanning electron micrograph of vancomicyn-resistant Staphylococcus aureusWIKIMEDIA, CDCThe antimicrobial properties of silver have been known for thousands of years, but it was not clear how the metal wreaked havoc on pathogenic invaders. Now, researchers have explained the cellular processes by which the precious metal weakens bacteria and makes them more susceptible to antibiotics, according to a study published yesterday (June 19) in Science Translational Medicine. The findings suggest that silver could be used to enhance the effectiveness of antibiotics against drug-resistant bacteria.
A team lead by Jim Collins, a biomedical engineer at Boston University, showed that dissolved silver ions interfere with several cellular processes in bacteria, including disulfide-bond formation, iron homeostasis, and metabolism. These changes not only make the cell membrane more permeable, but also lead to increased production of reactive oxygen species, which can induce cell death via DNA damage. (Last month, a report from a different group found that vitamin C has a similar effect on the bacteria that cause tuberculosis.)
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, ...
