The efficacy of photodynamic inactivation with laser diode on <em>Staphylococcus aureus</em> biofilm with various ages of biofilm

Abstract

Biofilms are able to casue microorganisms to be 80% more resistant to antibiotics. The extracelullar polymeric substance (EPS) in biofilm functions to protect bacteria, making it difficult for antibiotics to penetrate the biofilm layer. This study aims to determine the effective- ness of photodynamic inactivation with blue diode laser to reduce Staphylococcus aureus biofilm at various ages of biofilms. The light source is a 403 nm blue diode laser with an energy power of about 27.65±0.01 mW. The study was designed with two groups: Group C was the untreated control group with variations in age of biofilms (0; 6; 11; 17; 24; 32; 40 and 48) hours; Group T was a laser treatment group with variations in age of biofilm and energy density (4.23; 8.46; 12.70; 16.93 and 21.16) J/cm2. Biofilm reduction measurement method using ELISA test was performed to calculate OD595 value. The statistical analysis results of variance showed that there was an influence of biofilm age and irradiation energy density of laser on biofilm reduction. Optical density analysis showed the most optimum biofilm reduction happened when biofilm age is perfectly constructed (about 17 hours) and with 91% reduction. The longer biofilm age lived among those biofilms, the greater the reduction. The results of the Scanning Microscope Electron and fluorescent microscope measurement showed destruction site of the EPS biofilm and bacterial cell death. So, the activated photodynamic with 403 nm laser diode is effective to reduce the Staphylococcus aureus biofilm in the maturation phase.

Keywords

• laser diode
• biofilm ages
• Staphylococcus aureus
• energy density
• biofilm reduction