Ultraviolet light may reduce dental use of antibiotics

Friday 18 Sep 20


Paul Michael Petersen
Professor, Section Leader
DTU Fotonik
+45 46 77 45 12

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Antibiotic resistance can affect any person of any age in any country.
Source: WHO

The bacteria-killing properties of ultraviolet light can be harnessed to limit the use of antibiotics in dental treatment—e.g. infected root canals.

Bacteria in the oral cavity can cause infections, which in many cases are treated with antibiotics. Some infections may develop into chronic conditions—e.g. following the insertion of implants, or root canal treatments. Researchers from DTU Fotonik and the University of Copenhagen have developed a completely new principle that uses ultraviolet light to kill the bacteria—and which also significantly reduces the use of antibiotics. The solution called ‘light-assisted antibiotic treatment’ is a combination of UVB light and the antibiotic agent tobramycin. The UVB light used in the new type of treatment has a wavelength of about 300 nm and is part of natural daylight.

“The combination turns out to be just as effective as treating the bacterial infection with tobramycin at ten times the concentrations—in other words, it’s possible to reduce the use of antibiotics by a factor of ten if UVB-light is used in the treatment,” says Professor Paul Michael Petersen from DTU Fotonik, who has helped develop the principles. 

UVB light provides significant effect

The promising prospects of ‘light-assisted antibiotic treatment’ have so far only been demonstrated in the lab. Here, the researchers have grown biofilms of the bacterium, P. aeruginosa. A biofilm is an entire community of bacteria with a complex structure that improves the chances of survival for the bacteria in the biofilm—e.g. bacteria in biofilms can be ten to 1,000 times more resilient than if they appear ‘on their own’ and can therefore be difficult to kill using antibiotics. 

After 24 and 48 hours of growth, respectively, the cultivated biofilms were subjected to three different types of treatments—UVB light irradiation—or treatment with the antibiotics tobramycin and colistin. The UVB light was significantly better at wiping out the biofilms than the two antibiotics, but the big gain came when the researchers combined UVB light with tobramycin. By first irradiating the bacteria with UVB light and subsequently following up with tobramycin, the researchers achieved the significant effect comparable to ten times the concentration of tobramycin.

“Our results may offer a solution for the treatment of chronic oral infections that result from root inflammations or implant procedures. With light-assisted antibiotic treatment, we can reduce the consumption of antibiotics in dental patients,” says Paul Michael Petersen.

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