Electricity zaps could help prevent wound infections

A few zaps of electricity could be a potential alternative to antibiotics for preventing wound infections.

With electrical stimulation already in use in other areas of medicine, researchers experimented with small electrical currents to see how they would impact Staphylococcus epidermidis, a bacterium commonly found on human skin that can cause infections when entering wounds, and which has multiple antibiotic-resistant strains.

As Staphylococcus is part of the microbial ecosystem that naturally exists on the skin, the researchers preferred not to eradicate it, since its complete absence on the skin could cause other problems, said the paper’s co-senior author Gürol Süel of the University of California San Diego.

“Bacteria’s response to electricity isn’t well explored, partially because we don’t know the specific conditions under which bacteria will be excited,” said first author Saehyun Kim, also of the University of Chicago.

They found that small electric currents can elicit responses from S. epidermidis, but only in an acidic environment. The researchers call this characteristic selective excitability. Healthy human skin is mildly acidic, but chronic wounds tend to be neutral to basic.

“Discovering this selective excitability will help us discover how to control other bacteria species by looking at different conditions,” Kim said.

Further analysis also revealed that after electrical stimulation, the S. epidermidis showed a decrease in the expression of several genes, including those related to antibiotic resistance and biofilm formation.

The researchers designed a skin patch, called Bioelectronic Localized Antimicrobial Stimulation Therapy, or BLAST, to treat skin wounds by stimulating S. epidermidis under the right conditions. It contained electrodes and a hydrogel to provide an acidic environment. They tested the device on a pork skin inoculated with S. epidermidis. After the 18-hour treatment cycle, the team observed a significant decrease in biofilm coverage and nearly 10 times reduction in S. epidermidis cells compared to the untreated sample. They also tested the device on the surface of a catheter and saw the same antimicrobial effect.

In the right environment, electrical stimulation at a level 10 times below the safe limit for humans was able to stop 99% of biofilm formation, a clustering that can lead to infections, according to the researchers. When the environment pH is neutral, the treatment showed no effects.

Co-senior author Bozhi Tian, from the University of Chicago, said that with further research to examine the safety and effectiveness of this treatment, scientists could develop a wearable patch with a wireless circuit to control infections without drugs.

Image credit: iStock.com/Alex Liew