Blue Laser Inhibits Bacterial Growth of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa

Abstract

Objective: The purpose of this study was to analyze the influence of blue laser on bacterial growth of the main species that usually colonize cutaneous ulcers, as well as its effect over time following irradiation. Background data: The use of blue laser has been described as an adjuvant therapeutic method to inhibit bacterial growth, but there is no consensus about the best parameters to be used. Methods: Strains of Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, and Escherichia coli ATCC 25922 were suspended in saline solution at a concentration of 1.5 · 10 3 colony forming units (CFU)/mL. Next, 300 lL of this suspension was transferred to a microtitulation plate and exposed to a single blue laser irradiation (450 nm) at fluences of 0 (control), 3, 6, 12, 18, and 24 J/cm 2 . Each suspension was spread over the surface of a Petri plate before being incubated at 37°C, and counts of CFU were determined after 24 and 48 h. Results: Blue laser inhibited the growth of S. aureus and P. aeruginosa at fluences > 6 J/cm 2 . On the other hand, E. coli was inhibited at all fluences tested, except at 24 J/cm 2 . Conclusions: Blue laser light was capable of inhibiting bacterial growth at low fluences over time, thus presenting no time-dependent effect.

Antimicrobial blue light inactivation of pathogenic microbes: State of the art

“…de Sousa analyzed the influence of aBL emitted from a blue laser on the bacterial growth of S. aureus, P. aeruginosa, and E. coli (de Sousa et al, 2015b). Bacterial suspensions were exposed to a single exposure of a 450-nm blue laser at varying radiant exposures from 0 to 24 J/cm 2 .…”

Antimicrobial Efficacy of Irradiation with Visible Light on Oral BacteriaIn Vitro: A Systematic Review

“…de Sousa et al investigated the effect of blue light emitted from a laser (λ = 450 nm; 70 mW) on strains of S. aureus [25]. Growth was inhibited at fluences higher than 6 J/cm 2 (reduction of 22% for 6 J/cm 2 ; no higher inhibition rates detected for 12, 18 and 24 J/cm 2 ; no antibacterial effect [53] in any case).…”

The Effect of Irradiation with a 405 nm Blue-Violet Laser on the Bacterial Adhesion on the Osteosynthetic Biomaterials

“…Guffey and Wilborn reported that the irradiation with a 405 nm blueviolet laser had a bactericidal effect against S. aureus and Pseudomonas aeruginosa [27]. Other studies also reported that visible light is effective against Porphyromonas gingivalis, Fusobacterium nucleatum, Staphylococcus aureus, Streptococcus mutans, and Escherichia coli [28,29]. The results of our previous study also confirmed that the irradiation with a 405 nm blue-violet laser had a bactericidal effect against P. gingivalis which is a major periodontopathogenic microorganism as well as Prevotella intermedia, and even against Candida albicans which is a major responsible fungus causing candidiasis [30].…”