Electric skin patch offers a drug-free solution to bacterial infections

With a few shocks of electricity to the skin, researchers can stop bacterial infections without having to take medication. For the first time, researchers have developed a skin patch that uses imperceptible electrical currents to control microbes. The results will appear on October 24th in the journal Cell Press Device.

“This opens up exciting possibilities for drug-free treatments, particularly in skin infections and wound healing, where antibiotic-resistant bacteria pose a serious challenge,” says Bozhi Tian from the University of Chicago, one of the study’s senior co-authors.

Scientists already use electricity to manipulate mammalian cells, including humans, and to treat diseases without the use of drugs. Pacemakers, for example, can regulate the heartbeat by stimulating the heart muscles with small electrical currents. A retinal prosthesis, a type of bionic eye, also uses electricity to stimulate a patient's retina, partially restoring their vision.

Tian and his team wondered if they could manipulate bacteria using electricity instead of antibiotics – a traditional approach that triggered the global crisis of antibiotic resistance. Due to the overuse of antibiotics in humans and livestock, many microbes have evolved and become resistant to current medications, causing them to become less effective over time. Previous studies estimate that drug-resistant infections may have contributed to about 1.27 million deaths worldwide in 2019.

The team set out to test whether Staphylococcus epidermidisa common bacteria on human skin, would respond to electrical stimulation. S. epidermidiS is generally harmless and can even protect the skin from pathogens. However, if it enters the human body through a cut or medical procedure, such as a catheter, it can cause serious infections. Recently, three strains of S. epidermidis Resistance to all classes of antibiotics has emerged.

“Because Staphylococci “As part of the microbial ecosystem that naturally exists on our skin, we prefer not to eradicate it, as its complete absence from our skin could cause other problems,” says the paper's other co-senior author, Gürol Süel from the University of California at San Diego.

The team found that small electrical currents can cause reactions S. epidermidisbut only in an acidic environment. The researchers call this feature selective excitability. Healthy human skin is slightly acidic, but chronic wounds tend to be neutral to alkaline.

“The response of bacteria to electricity is not well understood, in part because we do not know the specific conditions under which bacteria are stimulated,” says lead author Saehyun Kim, also from the University of Chicago. “Discovering this selective excitability will help us figure out how to control other bacterial species by studying different conditions.”

The team stimulated the bacterium with a weak electrical voltage of 1.5 volts – significantly lower than the 15 volt limit considered undetectable and safe for humans – for 10 seconds every 10 minutes for 18 hours. Under ideal acidic conditions, the electricity treatment stopped 99% of biofilm, a collection of bacteria that block drugs and lead to persistent infections. If the pH of the environment is neutral, the treatment had no effect.

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

For the treatment of skin wounds through stimulation S. epidermidis under the right conditions, The team designed a skin patch called Bioelectronic Localized Antimicrobial Stimulation Therapy, or BLAST. The patch contains electrodes and a hydrogel to provide an acidic environment. They tested the device on pig skin inoculated with it S. epidermidis. After the 18-hour treatment cycle, the team observed a significant decrease in biofilm coverage and a nearly tenfold reduction S. epidermidis Cells compared to the untreated sample. They also tested the device on the surface of a catheter and found the same antimicrobial effect.

Tian says that with further research to study the safety and effectiveness of this treatment, scientists could develop a wearable patch with a wireless circuit to control infections without drugs.

The work is supported by the Bill & Melinda Gates Foundation, the US Army Research Office, the National Science Foundation and the National Institutes of Health.