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Lasers Med Sci (2009) 24:453460 DOI 10.1007/s10103-008-0588-5
REVIEW
Light sources for photodynamic inactivation of bacteria
Mihaela Antonina Calin & S. V. Parasca
Received: 12 December 2007 /Accepted: 26 May 2008 /Published online: 12 July 2008 # Springer-Verlag London Limited 2008
Abstract Bacteria have an important role in human and animal morbidity, and a great number of them have developed antibiotic resistance. In the past recent years a new way of dealing with this problem has been studied: photodynamic inactivation. This method is based on administration of a photosensitizing substance that fixes itself in the bacterial cell followed by exposure to a light source. In the experiments done by many researchers on photodynamic inactivation of bacteria, both coherent and non-coherent light sources were used. This article is a review of these light sources and of some experimental results obtained by different authors.
Keywords Bacteria . Light sources . Photodynamic inactivation . Photosensitizer
Introduction
Microscopic pathogens are widely spread in nature; numerous infection sources exist, and the unfit and prolonged antibiotic treatments have led to greater resistance of germs to these substances.
The permanent selection of new strands of antibiotic-resistant bacteria is, nowadays, a major problem in both human and veterinary medicine [1]. Among the germs with great resistance to antibiotics are Staphylococcus and Pseudomonas species. The methicillin-resistant Staphylococcus spp. or the one with multiple resistances (including beta lactamines macrolides, aminoglycosides) are difficult to deal with, mostly in the hospital environment [2].
In this context, modern research in microbiology and related domains (biophysics, chemistry, medicine, physics) were focused on the development of new methods of antimicrobial therapy, more efficient and faster, non-invasive and non-toxic, which would not lead to microbial resistance [3]. One of these non-invasive methods, based on the use of light sources, is the photodynamic inactivation of bacteria.
Photodynamic inactivation of bacteria consists of the administration of a photosensitizing substance that is fixed into the bacteria, followed by local irradiation with light (with a wavelength appropriate to the maximum absorption of the photosensitizer in use) to generate singlet oxygen, which leads to the death of the micro-organisms [4].
The mechanism of bacterial inactivation has not yet been elucidated. The idea is that inactivation of the bacteria by light radiation is produced, in principle, as follows:...