Antibiotics combined with photosensitizers: A novel approach to antibacterial treatment

The development of antibacterial methods passed through interrelations between two major techniques - antibiotic therapy and photodynamic treatment. The discovered in 1900 photodynamic inactivation of bacterial cells, was overshadowed by proposed in 1928 antibiotic therapy. The emergence of bacterial resistance to antibiotics led to serious questioning of the absolute power of these drugs and development of new technologies has become crucial in order to improve antimicrobial treatment. One of the solutions for this problem is based on the combined application of antibiotics and photosensitizers as a mixture of their free forms, after covalent conjugation, encapsulation into liposomes or immobilization of both components onto solid supports. Combined antibiotic-photosensitizer application shows good antibacterial activity against Gram-positive and Gram-negative bacteria at reduced antibiotic doses. The chapter discusses approaches to combining antibiotics with photosensitizers, analyses of the bactericidal activity of the combined preparations, and considers a possible synergetic mechanism for their action.