Effect of Diode Laser and UV Radiation on Methicillin-Resistant Staphylococcus Aureus on Blood Agar Medium

Background and Objective: bacteria and some pathogens like staphylococcus aureus living in plaque, are the main cause of many diseases. Regarding to Scientific advances and new approaches in microbiology, it s now possible to eliminate these bacteria in most efficient way. Inappropriate use of antibiotics has developed antibiotic-resistant strains of bacteria. In this study we are going to evaluate the effect of low power laser light, UV radiation and using both of these therapies in elimination of bacteria of microbial cultures.Materials and methods: this case-control study was conducted to evaluate the application of low power diode laser with a wave length of 660nm and 25volt power and UV radiation with a wave length of 480nm and 0.15 watt on methicillin-resistant S. aureus on blood agar medium. In this study, methicillin-resistant S. aureus was applied to blood agar plates using streak-plate method, one hour before exposure of the plates. A total of 40 plates of methicillin-resistant S. aureus were divided to 4 groups. Each group containing 10 plates of S. aureus culture media. Group 1 was exposed with UV radiation, group 2 with laser and group 3 with both laser and UV radiation. One group was considered as the control. All of the plates were taken out from the incubator at the same time. Group 1 was exposed 80 seconds by UV and group 2 was exposed 80 seconds by laser. Group 3 was exposed 80 seconds by laser and 80 seconds by UV subsequently. The last group remained unexposed. After the exposure, 30 plates of case groups (1, 2, 3) and 10 plates of control group were incubated in a 37degree temperature and 21 percent of humidity. The cultures were given 48 hours to develop colonies. Colonies in each plate were counted using bare eyes. The study was carried out again to assess the reliability of the results.Finding: 48 hours after exposure, the overall average of developed colonies in each group were determined. Group 3 (both laser and UV exposure) had the least average colonies (22/8) which is approximately 0/1 of control group average. The average of all groups were 104/58. Group 2 (exposure with laser) was second of least colony development with an average of 25/6 and group 1 (UV radiation) was third. Control group had the most developed colonies after 48 hours. According to average count of developed colonies in each group:Control group > group1 (UV radiation) > group2 (laser) > group3 (UV and Laser)Conclusion: although there is a reduction in growth rate of S. aureus using laser and UV radiation separately but it seems they have a synergistic effect when used together.

Keywords:

low power laser , UV , staphylococcus aureus