The antibacterial activity of blue light against nosocomial wound pathogens growing planktonically and as mature biofilms

Research output: Contribution to journalArticle


  • Fenella D Halstead
  • Joanne E Thwaite
  • Rebecca Burt
  • Thomas R Laws
  • Marina Raguse
  • Ralf Moeller
  • Beryl A Oppenheim


BACKGROUND: The blue wavelengths within the visible light spectrum are intrinisically antimicrobial, and can photodynamically inactivate the cells of a wide spectrum of bacteria (Gram-positive and -negative) and fungi. Furthermore, blue light is equally effective against both drug sensitive and resistant members of target species, and (in contrast to UV radiation), is less detrimental to mammalian cells. Blue light is currently used for treating acnes vulgaris, and Helicobacter pylori infections; the utility for decontamination and treatment of wound infections is in its infancy. Furthermore, limited studies have been performed on bacterial biofilms; the key growth mode of bacteria involved in clinical infections.Here we report the findings of a multicentre in vitro study performed to assess the antimicrobial activity of 400 nm blue light against bacteria in both planktonic and biofilm growth modes.

METHODS: Blue light was tested against a panel of 34 bacterial isolates (clinical and type strains) comprising: Acinetobacter baumannii, Enterobacter cloacae, Stenotrophomonas maltophilia, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Enterococcus faecium, Klebsiella pneumoniae, and Elizabethkingia meningoseptica.

RESULTS: All planktonic phase bacteria were susceptible to blue light treatment, with the majority (71%) demonstrating a ≥5 log10 decrease in viability after 15-30 minutes exposure (54 J/cm(2) to 108 J/cm(2)). Bacterial biofilms were also highly susceptible to blue light, with significant reduction in seeding observed for all isolates at all levels of exposure.

CONCLUSIONS: These results warrant further investigation of blue light as a novel decontamination strategy for the nosocomial environment, as well as additional wider decontamination applications.

IMPORTANCE: Blue light shows great promise as a novel decontamination strategy for the nosocomial environment, as well as additional wider decontamination applications (e.g. wound closure during surgery). This warrants further investigation.


Original languageEnglish
JournalApplied and Environmental Microbiology
Issue number11
Early online date29 Apr 2016
Publication statusPublished - Jun 2016