The combination of antimicrobial photocatalysis and antimicrobial photodynamic therapy to eradicate the extensively drug-resistant colistin resistant Acinetobacter baumannii

Background: The appearance of bacterial resistance to antibiotics a are major health problems. Antimicrobial photodynamic therapy (aPDT) has emerged as an adjunctive treatment for drug-resistant infections. Titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles have recently been proposed as effective carriers for photosensitizers. The present study was designed to evaluate the antibacterial activity of ZnO and TiO2 -nanoparticles accompanying aPDT and antimicrobial photocatalysis approaches against extensively drug-resistant colistin resistant Acinetobacter baumannii (XDR - CO-Ab). Materials and methods: A XDR - CO-Ab isolated from burn-wound infection was used in this study. The bacterial suspension was exposed to TBO (Toluidine blue O), TiO2, and ZnO-nanoparticles in different groups. Ultraviolet A (UVA) (320 nm) and blue laser light (405 nm) were used to activate the photosensitizer and nanoparticles. The bacterial viability was then determined by counting the number of colonies forming units (CFUs)/mL. Results: Using both aPDT and antimicrobial photocatalysis methods simultaneously, it had an amazing result; so that 99.32 % of XDR - CO-Ab was killed. According to the results, the bactericidal effects of activated TBO using UVA and laser lights was 5.1 % more than TBO was excited with laser light alone. Conclusions: It was found that the combination of photocatalyst (TiO2 + ZnO-nanoparticles) and TBO as photosensitizer at two-wavelength irradiation with blue laser and UVA lights have been shown to have significant antimicrobial effects.