Photoinactivation of clinical strains of Staphylococcus aureus using curcumin as photosensitizer agent

Abstract

Phytochemicals present excellent physicochemical properties that allow their application as photosensitizers. Herein, the efficacy of blue light to photoactivate curcumin (CU) and in turn promote it antimicrobial activity against two clinical strains of Staphylococcus aureus (CECT 976 and MJMC568-B), including methicillin-resistant (MRSA), was investigated. Additionally, the photodynamic antimicrobial effect of this plant secondary metabolite on the improvement of less effective antibiotics (mupirocin-Mup, methicillin-Met, tetracycline-Tet and tobramycin-Tob) was explored. The obtained results reveal that the photoactivation (420 nm, 30 mW/cm2, 10 min) of CU leads to a 32-fold reduction in its minimum inhibitory concentration (200 µg/mL). Only the combination of CU with Tob and Mup, showed a synergistic effect. These combinations were photoactivated and the CU-Tob combination promoted 100% of photoinactivation for MRSA strain. Photoactivated CU-Tob combination demonstrated for the first time a great antimicrobial potential for the treatment of S. aureus infections.