title: Laser disruption and killing of methicillin-resistant Staphylococcus aureus biofilms.
abstract: 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.
  
  
  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.
authors.affiliation: Department of Otolaryngology Head and Neck Surgery, St Luke's-Roosevelt Hospital, New York, NY 10019, USA. krespi@NYHNI.org
authors.forename: Yosef P
authors.initials: YP
authors.lastname: Krespi
authors.forename: Victor
authors.initials: V
authors.lastname: Kizhner
authors.forename: Laura
authors.initials: L
authors.lastname: Nistico
authors.forename: Luanne
authors.initials: L
authors.lastname: Hall-Stoodley
authors.forename: Paul
authors.initials: P
authors.lastname: Stoodley
mesh_terms: D018441:Biofilms / Q000187:drug effects / Q000528:radiation effects*; D002939:Ciprofloxacin / Q000494:pharmacology*; D003470:Culture Media; D019220:High-Energy Shock Waves; D006801:Humans; D066298:In Vitro Techniques; D028022:Low-Level Light Therapy; D055624:Methicillin-Resistant Staphylococcus aureus / Q000254:growth & development* / Q000502:physiology / Q000528:radiation effects*; D008826:Microbial Sensitivity Tests; D012016:Reference Values; D012680:Sensitivity and Specificity; D019265:Spectroscopy, Near-Infrared; D013203:Staphylococcal Infections / Q000188:drug therapy
chemical_list: D003470:Culture Media; D002939:Ciprofloxacin