title: Antimicrobial photodynamic inactivation of Staphylococcus aureus biofilms in bone specimens using methylene blue, toluidine blue ortho and malachite green: An in vitro study.
abstract: OBJECTIVE
  To evaluate the in vitro effectiveness of APDI with a 660 nm laser combined with methylene blue (MB), toluidine blue ortho (TBO) and malachite green (MG) dyes to inactivate Staphylococcus aureus (ATCC 25923) biofilms in compact and cancellous bone specimens.
  
  
  METHODS
  Eighty specimens of compact and 80 of cancellous bone were contaminated with a standard suspension of the microorganism and incubated for 14 days at 37°C to form biofilms. After this period, the specimens were divided into groups (n=10) according to established treatment: PS-L- (control - no treatment); PSmb+L-, PStbo+L-, PSmg+L- (only MB, TBO or MG for 5 min in the dark); PS-L+ (only laser irradiation for 180 s); and APDImb, APDItbo and APDImg (APDI with MB, TBO or MG for 180 s). The findings were statistically analyzed by ANOVA at 5% significance levels.
  
  
  RESULTS
  All experimental treatments showed significant reduction of log CFU/mL S. aureus biofilms when compared with the control group for compact and cancellous bones specimens; the APDI group's treatment was more effective. The APDI carried out for the compact specimens showed better results when compared with cancellous specimens at all times of application. For the group of compact bone, APDImg showed greater reductions in CFU/mL (4.46 log 10). In the group of cancellous bone, the greatest reductions were found in the APDImb group (3.06 log 10).
  
  
  CONCLUSIONS
  APDI with methylene blue, toluidine blue ortho and malachite green dyes and a 660 nm laser proved to be effective in the inactivation of S. aureus biofilms formed in compact and cancellous bone.
authors.affiliation: Multidisciplinary Health Institute, UFBA, Rua Rio de Contas, 58, Candeias, CEP 45029-094 Vitória da Conquista, BA, Brazil. Electronic address: drlucianorosa@yahoo.com.br.
authors.forename: Luciano Pereira
authors.initials: LP
authors.lastname: Rosa
authors.affiliation: Multidisciplinary Health Institute, UFBA, Rua Rio de Contas, 58, Candeias, CEP 45029-094 Vitória da Conquista, BA, Brazil.
authors.forename: Francine Cristina
authors.initials: FC
authors.lastname: da Silva
authors.affiliation: Multidisciplinary Health Institute, UFBA, Rua Rio de Contas, 58, Candeias, CEP 45029-094 Vitória da Conquista, BA, Brazil.
authors.forename: Sumaia Alves
authors.initials: SA
authors.lastname: Nader
authors.affiliation: Multidisciplinary Health Institute, UFBA, Rua Rio de Contas, 58, Candeias, CEP 45029-094 Vitória da Conquista, BA, Brazil.
authors.forename: Giselle Andrade
authors.initials: GA
authors.lastname: Meira
authors.affiliation: Multidisciplinary Health Institute, UFBA, Rua Rio de Contas, 58, Candeias, CEP 45029-094 Vitória da Conquista, BA, Brazil.
authors.forename: Magda Souza
authors.initials: MS
authors.lastname: Viana
mesh_terms: D000818:Animals; D018441:Biofilms / Q000187:drug effects*; D001842:Bone and Bones / Q000382:microbiology*; D002417:Cattle; D066298:In Vitro Techniques; D008751:Methylene Blue / Q000494:pharmacology; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000494:pharmacology*; D012394:Rosaniline Dyes / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects*; D014048:Tolonium Chloride / Q000494:pharmacology
chemical_list: D017319:Photosensitizing Agents; D012394:Rosaniline Dyes; C005095:malachite green; D014048:Tolonium Chloride; D008751:Methylene Blue
keywords: Biofilm; Malachite green; Methylene blue; Photodynamic therapy; Staphylococcus aureus; Toluidine blue