Fisioterapia e Pesquisa
On-line version ISSN 2316-9117
BENVINDO, Rogério Gubert; BRAUN, Graziela; CARVALHO, Alberito Rodrigo de and BERTOLINI, Gladson Ricardo Flor. Effects of photodynamic therapy and of a sole low-power laser irradiation on bacteria in vitro. Fisioter. Pesqui. [online]. 2008, vol.15, n.1, pp.53-57. ISSN 2316-9117. http://dx.doi.org/10.1590/S1809-29502008000100009.
Low-level laser therapy has been used to speed up healing process of pressure ulcers due to its antiinflammatory, analgesic, anti-edematous, and scarring effects. However there is no consensus on its effect on infected ulcers. The aim of this study was to verify the bactericidal effect of low-level laser therapy (InGaP, 670 nm) and photodynamic therapy (PDT) at 2, 4 and 6 J/cm2 doses, onto gram-negative and gram-positive bacteria in vitro. Thirty two Petri plates were prepared, 16 with Pseudomonas aeruginosa and 16 with Staphilococcus aureus, and divided into eight subgroups each: three subgroups treated with 2 J/cm2, 4 J/cm2, and 6 J/cm2 laser; three subgroups treated with 2 J/cm2, 4 J/cm2, and 6 J/cm2 PDT; one treated solely with photosensitiser; and a non-treated (control) subgroup. Laser and PDT groups were irradiated once and incubated for 24 hours; the other two subgroups underwent no irradiation. Cultures were visually analysed in search of inhibition haloes. In all subgroups, for both bacteria, no inhibition or growing signs could be detected. Hence neither low-level laser or PDT (InGaP, 670 nm) produced any bactericidal or bacteriostatic effect, nor any biostimulation effect, onto analysed bacteria.
Keywords : Bacteria [radiation effects]; Laser therapy, low level; Photochemotherapy [utilization].