The Impact of Light Parameters and Tetracycline Concentration on Antimicrobial Photodynamic Inactivation Against Drug Resistant <scp><i>Escherichia coli</i></scp>

ABL is an effective antimicrobial approach and recent studies indicated tetracycline has the ability to produce reactive oxygen species under blue light irradiation. However, the impact of light parameters and tetracycline concentration on the antimicrobial efficacy is not clear. In this study, we investigated the impacts of light dose, drug concentration, and irradiance on drug resistant Escherichia coli survival. The results showed the increase of light dose and drug concentration caused the increase in oxidative damage and bacterial death. Besides, we found the impact of irradiance on the combined antimicrobial effect was affected by the drug concentration. The results of photobleaching and dissolved oxygen showed the different rates of photochemical reaction under different irradiance. Finally, we proposed that suitable light treatment can be designed by varying the tetracycline concentration, light dose, and irradiance for different situations.