Patients who undergo surgery to receive hip or knee implants have a lot to look forward to, including comfort, mobility, and an improved quality of life. But they can also introduce a dangerous bacterial infection, since the body isn’t accustomed to the metal or plastic devices. To help prevent the spread of infections, researchers have developed a novel way of spotting it with the use of lasers and fluorescent antibiotics.

About one out of every 100 implant patients become infected after an operation. Spotting these infections can be especially difficult for surgeons though, as it’s not always clear whether the inflammation is caused by a bacterial infection — in which case the implant must be removed — or the body’s response to a foreign object. It becomes harder to diagnose the problem when bacteria surround themselves with a biofilm that protects from antibiotics.

The researchers used a technique for tracking the spread of cancer, in which laser light activated fluorescent dyes in affected areas of the body, causing them to light up. “You don’t have to perform surgery, take a sample, [and] cultivate the bacteria,” Jan Maarten van Dijl, a microbiologist at the University of Groningen in the Netherlands, told LiveScience. “Now, with this fluorescent dye, we would have a tool that would allow bedside monitoring.”

Van Dijl and his team infected mice with Staphylococcus aureus, and then injected the antibiotic vancomycin — both were modified to contain a fluorescent molecules (the antibiotic was red and the infection was blue). The fluorescent molecules became excited when the researchers shone a camera emitting a laser beam on the mice, and appeared as a faint glow through the skin.

After testing the fluorescent antibiotic on a human ankle from a cadaver, they found similar results. But they also found that “it will only work as deep as the laser light and fluorescence can go through the tissue,” van Dijl told LiveScience. The fluorescent molecule would also have to be tested for toxicity in humans with regards to dosing, but since it’s been used in humans before, and the antibiotic is safe, van Dijl says there’s a good chance they are safe together.

Source: van Oosten M, Schafer T, Gazendam J, et al. Real-time in vivo imaging of invasive- and biomaterial-associated bacterial infections using fluorescently labelled vancomycin. Nature Communications. 2013.