Danish Researchers Demonstrate Test Use of UV Light to Treat In Vitro Bacterial Biofilms

A group of Danish researchers tested the use of UV light to reduce the amount of antibiotic needed for the eradication of in vitro biofilms. The researchers point out that the problem of antibiotic resistance has lead doctors to seek alternatives to antibiotics for treatment. One such treatment that the researchers looked into was the use of UV light, which had previously been used to sterilize drinking water.

Biofilms Difficult to Treat with Antibiotics

According to the researchers, biofilms are particularly difficult to treat with antibiotics, because the physical barrier of the biofilm matrix, limits the diffusion of the antibiotic molecules into the biofilm, thereby reducing antimicrobial penetration.

For this reason, the researchers decided to test the use of UV LED light at various wavelengths, both by itself and in combination with antibiotics to gauge its effectiveness in treating in vitro bacterial biofilms.

They tested wavelengths of 239 nm to 338 nm with approximate increments of 5 nm to find the optimum wavelength for eradicating the biofilms.

The researchers demonstrated that the use of the UV LED in vitro with specific wavelengths in a narrow range around 296 nm (in the UV-B range)  are able to eradicate bacteria in the biofilm state (grown for 24 hours) more effectively, than antibiotics. Furthermore, they demonstrated that combining irradiation and antibiotics works even better.

The found that the eradication efficacies, on mature biofilms, that light assisted antibiotic and the using the antibiotic by itself with about ten times greater concentration, were equivalent. They thereby introduced the concept of light assisted antibiotics as a potential treatment option. The researchers published their findings in the journal Scientific Reports.


A. Argyraki, M. Markvart, et al. UV light assisted antibiotics for eradication of in vitro biofilms, Scientific Reports, volume 8, Article number: 16360 (2018).

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