As scary as it is to admit, there will come a point where antibacterial hand sanitizers will no longer be enough. However, new research has found that silver — yes a metal — can potentially help our fight against harmful bacteria.

The World Health Organization (WHO) has reported that many bacteria that can cause serious ailments in humans, like staphylococcus infections, tuberculosis, and malaria have become resistant to the antibiotic drugs that could once effectively kill them off and prevent further infection. WHO explains that resistance of bacteria to antibiotics can prolong illness and cause greater death rates. They report, "The death rate for patients with serious infections treated in hospitals is about twice that in patients with infections caused by non-resistant bacteria."

Small particles of silver have been used for some time as antimicrobial agents. A 2007 study indicated that silver has been used topically since the 1940s to prevent wound infection. It has also been used without incidence of resistance for so long because of its mechanism of action.

Its mechanism cannot be avoided by the targeting bacteria because silver does not alter just one part, but multiple parts of the bacteria. Antibiotics, mainly, work to deteriorate a bacteria's outermost membrane. It usually pricks a hole into it or otherwise destroys it. As bacteria are single-called organism, the protection of their livelihood is based on the integrity of that membrane. However, bacteria can become resistant when they strengthen their membranes, becoming impervious to the attacks from antibiotics.

Silver, as proposed by a new study done at the Howard Hughes Medical Institute, alters cellular processes that keep the bacteria alive, such as its metabolism, internal iron and silver levels, and its ability to form bonds between vital proteins. The researchers also found that silver works to increase the amounts of oxygen present in the bacteria; bacteria often cannot handle high levels of oxygen and often that alone will kill a bacteria.

In an experiment on biofilms, which are groups of very hardy bacteria that can form anywhere, from the bottoms of boats to sewage filters, adding silver to existing antibiotic treatments increased its ability to fight the bacteria in the hardy biofilm. The silver helped the antibiotic kill off 100 times more bacterial cells than the antibiotic alone. This data is promising, as antibiotics alone are no match for biofilms.

Adding silver can even increase antibiotic susceptibility of bacteria; in an experiment where established drug resistant bacteria were given silver, their susceptibility to being eradicated by antibiotics reached normal levels. This was shocking, as without the silver, the bacteria thrived in the face of antibiotics, but given silver, they died as easily as nonresistant forms.

Now, the addition of silver to test tubes and petri plates of bacteria may not sound terrible, but what about silver's implications in people? In a toxicity measurement performed on mice up to 48 hours after treatment, researchers found that levels of silver in the blood did not persist for more than two days, and did not cause any adverse effects to major organs like the kidney or liver, when the mice were given small doses. This is key, because in the study, low concentrations of silver were all that were needed to get antibiotics to work effectively once more.

The addition of silver can also reduce the amount of antibiotics needed to treat an infection. The researchers found that adding a small amount of silver corresponded to a twofold decrease in the amount of antibiotic needed to eradicate the infection. This is likely because the silver makes the antibiotic's job easier, and so it does not have to outnumber the bacteria anymore. It simply needs to kill them off after the silver weakens them.

The uses of silver in addition to antibiotics is quite promising. Nothing has yet been established about dosages in humans, but the researchers concluded that the release of these antimicrobials at the site of infection could prove very useful.

So, if, in a few years, antibacterial hand sanitizers begin to sparkle, silver may very well be the reason why.


Source: Morones-Ramirez JR, WInkler JA, Spina CS, Collins JJ. Silver Enhances Antibiotic Activity Against Gram-Negative Bacteria. Science Tranlsational Medicine. 2013.