title: In vitro effectiveness of antimicrobial photodynamic therapy (APDT) using a 660 nm laser and malachite green dye in Staphylococcus aureus biofilms arranged on compact and cancellous bone specimens.
abstract: The aim of this study was to evaluate the in vitro effectiveness of antimicrobial photodynamic therapy (APDT) using a 660 nm visible laser combined with malachite green (MG) dye in the inactivation of Staphylococcus aureus (ATCC 25923) biofilms formed within compact and cancellous bone specimens. Specimens of 80 compact bones and 80 cancellous bones were contaminated with a standard suspension of S. aureus and incubated for 14 days at 37 °C to allow for the formation of biofilms. The specimens were divided into the following groups (n = 10) according to the treatment conditions: PS-L - (control - no treatment), PS+L - (only MG for 5 min), PS-L + 90 (only laser irradiation for 90 s), PS-L + 180 (only laser irradiation for 180 s), PS-L + 300 (only laser irradiation for 300 s), APDT90 (APDT for 90 s), APDT180 (APDT for 180 s), and APDT300 (APDT for 300 s). The findings were statistically analyzed using an ANOVA 5%. All of the experimental groups were significantly different from the control group for both the compact and cancellous bone specimens. The compact bone specimens that received APDT treatment (for either 90, 180, or 300 s) showed reductions in the log10 CFU/ml of S. aureus by a magnitude of 4 log10. Cancellous bone specimens treated with 300 s of APDT showed the highest efficacy, and these specimens had a reduction in S. aureus CFU/ml by a factor of 3 log10. APDT treatment using these proposed parameters in combination with MG was effective at inactivating S. aureus biofilms in compact and cancellous bone specimens.
authors.affiliation: Multidisciplinary Health Institute, Federal University of Bahia, Rua Rio de Contas, 58, Candeias, Vitória da Conquista, BA, 45029094, Brazil, drlucianorosa@yahoo.com.br.
authors.forename: Luciano Pereira
authors.initials: LP
authors.lastname: Rosa
authors.forename: Francine Cristina
authors.initials: FC
authors.lastname: da Silva
authors.forename: Sumaia Alves
authors.initials: SA
authors.lastname: Nader
authors.forename: Giselle Andrade
authors.initials: GA
authors.lastname: Meira
authors.forename: Magda Souza
authors.initials: MS
authors.lastname: Viana
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry*; D018441:Biofilms / Q000528:radiation effects*; D001842:Bone and Bones / Q000187:drug effects / Q000382:microbiology* / Q000528:radiation effects; D002417:Cattle; D004396:Coloring Agents / Q000737:chemistry*; D053685:Laser Therapy / Q000379:methods; D007834:Lasers; D010778:Photochemotherapy / Q000379:methods*; D012394:Rosaniline Dyes / Q000737:chemistry*; D013211:Staphylococcus aureus / Q000528:radiation effects*; D013977:Tibia / Q000187:drug effects / Q000382:microbiology / Q000528:radiation effects
chemical_list: D000890:Anti-Infective Agents; D004396:Coloring Agents; D012394:Rosaniline Dyes; C005095:malachite green