OBJETIVO: Avaliar in vitro o efeito antibacteriano do laser diodo com comprimento de onda de 650nn, associado a substancia fotossensível azul de toluidina sobre as bactérias de ulceras cutâneas infectadas. MÉTODOS: Foram coletadas amostras através de um swab com meio de transporte, de material infectado de úlceras cutâneas. Os materiais foram inoculadas em meios de cultura contendo ágar sangue azida para o crescimento de bactérias gram-positivas e agar Mac Conkey para as gram-negativas, e incubadas por 48 horas. Os resultados obtidos da contagem das unidades formadoras de colônias foram relacionados e submetidos a analise estatística adotando como nível de significância p > ou = 0.05. RESULTADOS: Os resultados da análise de variância ANOVA para a media geral foi p= 0,0215 e para o post hoc test teste t. TBO x Controle p=0,0186, TBO + Laser x Controle p=0,0039. CONCLUSÃO: Houve redução, significativa das unidades formadoras de colônias quando submetidas à terapia fotodinâmica.

PURPOSE: To evaluate in vitro the antibacterial effect of diode laser light of wavelength 650 nm, in association with the photosensitive substance toluidine blue, on the bacteria in infected skin ulcers. METHODS: Samples were collected by means of swabs containing a medium for transporting infected material from skin ulcers. The material was inoculated into culturing medium containing azide blood agar for the growth of Gram-positive bacteria, and MacConkey agar for Gram-negative bacteria, and incubated for 48 hours. The results obtained from counting the colony-forming units were correlated and subjected to statistical analysis, adopting the significance level of p > or = 0.05. RESULTS: From analysis of variance (ANOVA), the result for the general mean was p = 0.0215. Using the t test with post-hoc test, the result for TBO vs. Control was p = 0.0186, and for TBO + Laser vs. Control it was p = 0.0039. CONCLUSION: There was a significant reduction in colony-forming units when the cultures were subjected to photodynamic therapy.