Synergistic effect

The researchers, based at the government-owned Crown Research Institute AgResearch, combined two wavelengths – far-UVC (222 nm) and blue LED light (405 nm) – to deactivate an antibiotic-resistant bacterium, specifically extended-spectrum β-lactamase-producing (ESBL) Escherichia coli. They outline the results of their research in the Journal of Applied Microbiology.

As co-author and project leader Gale Brightwell explains, the unique aspect of the approach is the synergistic effect achieved by combining the two wavelengths. This results in superior efficiency compared with using these wavelengths individually, and utilizes distinct antimicrobial mechanisms that "work together to effectively deactivate bacteria".

"We believe the blue light inflicts the initial damage to the bacterial cells, making them more vulnerable, and far-UVC then capitalizes on this weakened state to exert its antimicrobial effects more efficiently," says Brightwell, principal scientist and science team leader for the AgResearch Food System Integrity Team.

Sustainable solution

According to co-author Amanda Gardner, a research associate at AgResearch, the new technology could be used to combat bacterial contamination in a number of environments –  including healthcare facilities and food processing plants, as well as water treatment plants and public spaces like airports, schools and public transport. She notes, however, that further research is needed to "fully understand the health impacts, establish optimal dosages, and ensure the technology's safe and effective use in clinical settings".

"The study's advance lies in demonstrating the effectiveness of the dual-light technology against antibiotic-resistant bacteria without promoting further resistance," Gardner explains. "However, addressing the development of light tolerance in bacteria and verifying its performance under practical conditions are crucial steps to maximize the positive impact of this technology in clinical and real-world settings."