Laser disruption and killing of methicillin-resistant Staphylococcus aureus biofilms

Am J Otolaryngol. 2011 May-Jun;32(3):198-202. doi: 10.1016/j.amjoto.2010.01.010. Epub 2010 Apr 30.


Objective: The aim of the study was to study the efficacy of 2 different lasers in vitro, in disrupting biofilm and killing planktonic pathogenic bacteria.

Materials and methods: Biofilms of a stable bioluminescent of Staphylococcus aureus Xen 31 were grown in a 96-well microtiter plate for 3 days. The study included 7 arms: (a) control; (b) ciprofloxacin (3 mg/L, the established minimum inhibitory concentration [MIC]) alone; (c) shock wave (SW) laser alone; (d) near-infrared (NIR) laser alone; (e) SW laser and ciprofloxacin; (f) SW and NIR lasers; (g) SW, NIR lasers, and ciprofloxacin. The results were evaluated with an in vivo imaging system (IVIS) biophotonic system (for live bacteria) and optical density (OD) for total bacteria.

Results: Without antibiotics, there was a 43% reduction in OD (P < .05) caused by the combination of SW and NIR suggesting that biofilm had been disrupted. There was an 88% reduction (P < .05) in live biofilm. Ciprofloxacin alone resulted in a decrease of 28% of total live cells (biofilm remaining attached) and 58% of biofilm cells (both P > .05). Ciprofloxacin in combination with SW and SW + NIR lasers caused a decrease of more than 60% in total live biomass and more than 80% of biofilm cells, which was significantly greater than ciprofloxacin alone (P < .05).

Conclusions: We have demonstrated an effective nonpharmacologic treatment method for methicillin-resistant Staphylococcus aureus (MRSA) biofilm disruption and killing using 2 different lasers. The preferred treatment sequence is a SW laser disruption of biofilm followed by NIR laser illumination. Treatment optimization of biofilm is possible with the addition of ciprofloxacin in concentrations consistent with planktonic MIC.

Publication types

  • Comparative Study

MeSH terms

  • Biofilms / drug effects
  • Biofilms / radiation effects*
  • Ciprofloxacin / pharmacology*
  • Culture Media
  • High-Energy Shock Waves
  • Humans
  • In Vitro Techniques
  • Low-Level Light Therapy*
  • Methicillin-Resistant Staphylococcus aureus / growth & development*
  • Methicillin-Resistant Staphylococcus aureus / physiology
  • Methicillin-Resistant Staphylococcus aureus / radiation effects*
  • Microbial Sensitivity Tests
  • Reference Values
  • Sensitivity and Specificity
  • Spectroscopy, Near-Infrared
  • Staphylococcal Infections / drug therapy


  • Culture Media
  • Ciprofloxacin