Antibiotic-resistant bacteria are posing an ever-increasing threat to humanity. As microbes mutate in ways that allow them to fend off our methods of defense, they become a bigger and bigger danger to our health. Now, scientists have come up with an innovative way to spot antibiotic-resistant infections early, which could help us treat them more effectively and limit their spread.

A team from the Chinese Academy of Sciences has created a bandage that changes color depending on whether a bacterial infection is present and whether it is resistant to antibiotics. It’s basically a handy kind of medical traffic light system.

If a wound isn’t infected, the paper-based bandage remains a green color. However, if bacteria invade, it turns yellow in response to the change in acidity that comes with an infection. The material then releases an antibiotic, quickly targeting the infection before it gets the chance to cause too much damage and spread. If the infection can’t be treated because the bacteria are drug-resistant, the bandage turns red in response to enzymes released at the site of infection.

If the bandage-wearer is this unlucky, a light can be shone on the bandage to activate a reactive oxygen species that kills or weakens the bacteria, making the infection more susceptible to antibiotics. A reactive oxygen species is a chemical substance that produces a kind of oxygen that harms the bacteria when activated by a specific wavelength of light.

The color changes seen when a drug-sensitive (DS) infection is present compared to a drug-resistant (DR) infection. Adapted from ACS Central Science 2020, DOI: 10.1021/acscentsci.9b01104

So far, the bandage has only been tested out on mice, not people, but the team found that it successfully sped up the healing of wounds infected with both drug-sensitive and drug-resistant bacteria. In their experiment, the team focused on E. coli infections and found that their band-aid could differentiate between antibiotic-resistant infections and infections easily treatable with drugs.

The World Health Organization describes antibiotic resistance as “one of the biggest threats to global health, food security, and development today.” Antibiotic-resistant microbes are much harder to kill than those susceptible to our arsenal of medicines. Often antibiotics are over-prescribed, can be bought without a prescription, or are indiscriminately given to livestock. This means they permeate our environment, giving bacteria the opportunity to encounter them and evolve strategies to overcome their microbe-killing powers.

It is essential that we reduce our use of antibiotics, identify new ones, and find ways of targeting antibiotic-resistant bugs.

“Our design can alleviate off-target side effects, maximize therapeutic efficacy, and track the drug resistance in real-time with the naked eye,” the researchers write in ACS Central Science. “This work develops a new way for the rational use of antibiotics. Given the low cost and easy operation of this point-of-care device, it can be developed for practical applications.”