title: Violet 405-nm light: a novel therapeutic agent against common pathogenic bacteria.
abstract: The increasing incidence of healthcare-associated infections (HAIs) and multidrug-resistant organisms demonstrate the need for innovative technological solutions. Staphylococcus aureus, Streptococcus pneumonia, Escherichia coli, and Pseudomonas aeruginosa in particular are common pathogens responsible for a large percentage of indwelling medical device-associated clinical infections. The bactericidal effects of visible light sterilization (VLS) using 405-nm is one potential therapeutic under investigation.
  
  
  
  Light-emitting diodes of 405-nm were used to treat varying concentrations of S aureus, S pneumonia, E coli, and P aeruginosa. Irradiance levels between 2.71 ± 0.20 to 9.27 ± 0.36 mW/cm2and radiant exposure levels up to 132.98 ± 6.68 J/cm2were assessed.
  
  
  
  Dose-dependent effects were observed in all species. Statistically significant reductions were seen in both Gram-positive and Gram-negative bacteria. At the highest radiant exposure levels, bacterial log10reductions were E coli-6.27 ± 0.54, S aureus-6.10 ± 0.60, P aeruginosa-5.20 ± 0.84, and S pneumoniae-6.01 ± 0.59. Statistically significant results (<0.001*) were found at each time point.
  
  
  
  We have successfully demonstrated high-efficacy bacterial reduction using 405-nm light sterilization. The VLS showed statistical significance against both Gram-positive and Gram-negative species with the given treatment times. The β-lactam antibiotic-resistant E coli was the most sensitive to VLS, suggesting light therapy could a suitable option for sterilization in drug-resistant bacterial species. This research illustrates the potential of using VLS in treating clinically relevant bacterial infections.
authors.affiliation: School of Medicine, Oregon Health and Sciences University, Portland, Oregon; Department of Health Sciences, Center for Medical Innovation, University of Utah, Salt Lake City, Utah. Electronic address: Barneck@ohsu.edu.
authors.forename: Mitchell D
authors.initials: MD
authors.lastname: Barneck
authors.affiliation: Department of Health Sciences, Center for Medical Innovation, University of Utah, Salt Lake City, Utah.
authors.forename: Nathaniel L R
authors.initials: NLR
authors.lastname: Rhodes
authors.affiliation: School of Medicine, University of Utah, Salt Lake City, Utah.
authors.forename: Martin
authors.initials: M
authors.lastname: de la Presa
authors.affiliation: Department of Health Sciences, Center for Medical Innovation, University of Utah, Salt Lake City, Utah.
authors.forename: James P
authors.initials: JP
authors.lastname: Allen
authors.affiliation: Department of Bioengineering, University of Utah, Salt Lake City, Utah.
authors.forename: Ahrash E
authors.initials: AE
authors.lastname: Poursaid
authors.affiliation: Department of Health Sciences, Center for Medical Innovation, University of Utah, Salt Lake City, Utah.
authors.forename: Maziar M
authors.initials: MM
authors.lastname: Nourian
authors.affiliation: Department of Surgery, University of Utah, Salt Lake City, Utah.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Firpo
authors.affiliation: Department of Surgery, University of Utah, Salt Lake City, Utah.
authors.forename: John T
authors.initials: JT
authors.lastname: Langell
mesh_terms: D003428:Cross Infection / Q000517:prevention & control*; D004926:Escherichia coli / Q000528:radiation effects*; D006801:Humans; D008027:Light; D011550:Pseudomonas aeruginosa / Q000528:radiation effects*; D013211:Staphylococcus aureus / Q000528:radiation effects*; D013242:Sterilization / Q000379:methods*; D013296:Streptococcus pneumoniae / Q000528:radiation effects*
keywords: 405 nm light; Antibiotic resistance; Gram-negative; Gram-positive; Sterilization; Visible light