Photodynamic inactivation of antibiotic‐resistant Gram‐positive bacteria: Challenges and opportunities.

The growing numbers of pathogenic bacteria acquiring multidrug resistance are posing the challenges to develop novel therapeutic approaches. Photodynamic bacterial inactivation assaults multiple subcellular targets of pathogenic bacteria, including Staphylococcus aureus, with low tendency to induce further resistance. A wide range of aPDI photosensitizers were investigated for localized infections, including endogenous porphyrins and encapsulated sensitizers in nanoparticles. This mini review presents the concepts of aPDI, a field consisting of more than 3000 research articles published over 30 years. Mutated PBP membrane enzymes of multiantibiotic resistant S. aureus are plausible targets of aPDI. Synergistic aPDI using simultaneously DP, light irradiation and the antibiotic oxacillin, was recently described, eliminating temporarily oxacillin resistance. Additive antimicrobial effects were achieved with DP‐aPDI combined with additional classes of antibiotics. We propose that mutual aPDI adjuvant with antibiotics or other toxic molecules is opening a new therapeutic window for topical life‐threatening infections, without induction of further resistance. [ABSTRACT FROM AUTHOR]