title: Effects of low intensity laser irradiation during healing of infected skin wounds in the rat.
abstract: OBJECTIVE
  Low intensity laser irradiation remains a controversial treatment for non-healing wounds. This study examines the effect of low intensity light on healing of infected skin wounds in the rat.
  
  
  METHODS
  Wounds on the rat dorsum were inoculated withPseudomonas aeruginosa. Wounds were irradiated or sham-irradiated three times weekly from day 1 to 19 using 635-nm or 808-nm diode lasers delivering continuous wave (CW) or intensity modulated (3800 Hz) laser radiation, all at radiant exposures of 1 and 20 J/cm2. Wound area and bacterial growth on the wound surface were evaluated three times a week. Histological and immunohistochemical analyses were performed at day 8 and 19.
  
  
  RESULTS
  Wounds that were irradiated using a wavelength of 635 nm (1 and 20 J/cm2) or intensity modulated 808-nm laser light at 20 J/cm2were smaller in area at day 19 than the sham-irradiated controls (achieved significance level=0.0105-0.0208) and were similar to controls in respect of bacterial growth. The remaining light protocols had no effect on wound area at day 19 although they increasedStaphylococcus aureusgrowth across the time line compared with controls (p<0.0001 top<0.004). CW 808-nm light at 20 J/cm2significantly delayed half-heal time. Histological and immunohistochemical analyses supported wound closure findings: improved healing was associated with faster resolution of inflammation during the acute phase and increased signs of late repair at day 19. Significant inflammation was seen at day 19 in all irradiated groups regardless of radiant exposure, except when using 635 nm at 1 J/cm2.
  
  
  CONCLUSIONS
  Red light improved healing of wounds. Only one 808-nm light protocol enhanced healing; lack of benefit using the remaining 808-nm light protocols may have been due to stimulatory effects of the light onS. aureusgrowth.
authors.affiliation: Departments of Physical Therapy, Mount Sinai Hospital, University of Toronto, 500 University Ave, Toronto, ON M5G 1X5, Canada.
authors.forename: Ethne L
authors.initials: EL
authors.lastname: Nussbaum
authors.affiliation: Department of Laboratory Medicine and Pathobiology, Mount Sinai Hospital, University of Toronto, 500 University Ave, Toronto, ON M5G 1X5, Canada.
authors.forename: Facundo Las
authors.initials: FL
authors.lastname: Heras
authors.affiliation: Department of Laboratory Medicine and Pathobiology, Mount Sinai Hospital, University of Toronto, 500 University Ave, Toronto, ON M5G 1X5, Canada.
authors.forename: Kenneth P H
authors.initials: KP
authors.lastname: Pritzker
authors.affiliation: Department of Microbiology, Mount Sinai Hospital, University of Toronto, 500 University Ave, Toronto, ON M5G 1X5, Canada.
authors.forename: Tony
authors.initials: T
authors.lastname: Mazzulli
authors.affiliation: Department of Medical Biophysics, University of Toronto, 610 University Avenue, Rm. 7-418, Toronto ON M5G 2M9, Canada.
authors.forename: Lothar
authors.initials: L
authors.lastname: Lilge
keywords: bacteria; histology; immunohistochemistry; phototherapy; wound healing