We selected 20 strains of bacteria for this project. Antimicrobial susceptibility was performed using Kirby- Bauer method; the most resistant Klebsiella pneumoniae isolate to 12 antibiotics was selected and irradiated by laser light. The antimicrobial effect of different MB concentrations and laser doses were evaluated for determining the optimal PHDT parameters. Four experimental groups were included: group1: photosensitizer alone, group2: laser diode irradiation alone, group3: combination of MB and laser irradiation. Influence of laser light doses (4.8, 9.6, 14, and 19J/cm2) in association with different MB concentrations (30, 50, 70, and 90μg/ml. CFU/ml were performed to estimate the viability of bacteria. The antimicrobial effect of PHDT was assessed with percent of reduction in viable count. The antimicrobial effect of PHDT on K. pneumoniae was dose dependent to laser light. In group1, without laser irradiation did not show any antimicrobial effect on K. pneumoniea, in group2, laser irradiation alone with 20mw/cm2 and different doses (4.8, 9.6, 14, and 19J/cm2) did not modify bacterial growth. Group3, significant difference in viability of bacteria after treatment by PHDT. The adequate PHDT parameters were light irradiance 20 mw/cm2, and MB concentration 50μg/ml and exposure time 12min, dose 14J/cm2. Complete killing of K.pneumoniea at a dose 19J/cm2 and MB concentration 90μg/ml.

Burn Wounds, Photodynamic Therapy (PHDT), Mediated Photodynamic Therapy (PDT).