ABSTRACT
Inflamed, infected tissues and cellular debris have been shown to accumulate photosensitizing compounds such as hematoporphyrin derivative. Upon illumination, phagocytosed bacteria within macrophages, as well as the macrophages themselves, are destroyed by the resultant photodynamic effects. Cell wall deficient bacteria of the Mycoplasma group have been described to be inactivated by porphyrins in a way similar to that of gram-positive or eukaryotic cells. Strains of S. aureus, sensitive and resistant to antibiotics, were equally inactivated by photodynamic treatment. Specific inactivation of viruses and cell-associated virions, with considerable safety to normal uninfected or untransformed cells, is a crucial medical problem in controlling viral infections. The cumulative effort of many research groups has resulted in the development of the photodynamic treatment modality against gram-positive and gram-negative bacteria, viral complexes, and virally infected cells. The antibacterial activity of porphyrin-induced PDT shows unique properties. The chapter shows that the binding of porphyrin molecules to the bacterial cell is a prerequisite for the photoinactivation process.
