Evaluation of the efficacy of photodynamic antimicrobial therapy using a phenothiazine compound and Laser (λ=660ηm) on the interface: macrophage vs S. aureus

摘要

Nowadays photodynamic inactivation has been proposed as an alternative treatment for localized bacterial infections as a response to the problem of antibiotic resistance. Much is already known about the photodynamic inactivation of microorganisms: both antibiotic-sensitive and -resistant strains can be successfully photoinactivated and there is the additional advantage that repeated photosensitization of bacterial cells does not induce a selection of resistant strains. Staphylococcus spp. are opportunistic microorganisms known for their capacity to develop resistance against antimicrobial agents. The emergence of resistant strains of bacteria such as methicillui-resistant Staphylococcus aureus (MRSA) poses a major challenge to healthcare. MRSA is a major cause of hospital-acquired infection throughout the world and is now also prevalent in the community as well as nursing and residential homes. The aim of this study was to evaluate the phagocytic function of macrophages J774 against S. aureus in the presence and absence of AmPDT with phenothiazine compound (12.5 μg/mL) and low level laser (λ=660nm, 12 J/cm~2). Experimental groups: Control group (L-P-), Phenothiazine group (L-P+) Laser group (L+P-), AmPDT group (L+P+).The tests presented in this study were performed in triplicate. This study showed that AmPDT induced bacterial death in about 80% as well as increasing phagocytic capacity of macrophages by approximately 20% and enhanced the antimicrobial activity by approximately 50% compared to the control group and enabling more intense oxidative burst.