Bactericidal effect of photodynamic therapy against methicillin-resistant Staphylococcus aureus strain with the use of various porphyrin photosensitizers.

Abstract

Photodynamic therapy (PDT) is based on photosensitizers activated by light of appropriate wavelength. Their activation leads to generation of singlet oxygen and free radicals responsible for the cytotoxic effect. The aim of this project was to compare the bactericidal effect of PDT using different porphyrin photosensitizers against a methicillin-resistant Staphylococcus aureus strain. Exogenous sensitizers (protoporphyrin IX and newly synthesized derivative, protoporphyrin diarginate) induced a 3 log10-unit reduction in bacterial viable counts. With the use of endogenous, ALA-induced porphyrins, a 1.6 log10-unit reduction was obtained. The sensitizers tested executed their antibacterial activity with no essential change in the antibiotic resistance pattern of the studied strain.

The synergistic effect of PDT and oxacillin on clinical isolates of Staphylococcus aureus

“…Other studies that tested the combination of antibiotics and PDT used the disk diffusion method to detect synergistic combinations . In these experiments, S. aureus cultures were treated with PDT and subcultured on TSA medium.…”

Alternative therapies in Staphylococcus aureus diseases.

“…Up to now mainly preliminary investigations have been performed, such as analyzing the survival rate of bacteria in vitro, depending on the type and dose of the photosensitizer, wavelength and illumination duration (Maisch et al, 2005;Grinholc et al, 2007a;Sharma et al, 2008;Peloi et al, 2008).…”

“…From a clinical point of view, an important issue is easy killing of the multi-resistant MRSA strains in response to photodynamic therapy as development of resistance to this therapy seems to be unlikely, in contrast to the quick gaining of resistance towards different antibiotics and other antibacterial agents (Hamblin & Hasan, 2004;Grinholc et al, 2007a). Grinholc et al (2008b) reported that the response to photodynamic inactivation with protoporphyrin diarginate (PPArg 2 ) was different among various clinical MSSA and MRSA strains and ranged from 0 to 3 log 10 unit reduction in viable counts.…”

Evaluation of the Role of the Pharmacological Inhibition of Staphylococcus aureus Multidrug Resistance Pumps and the Variable Levels of the Uptake of the Sensitizer in the Strain‐Dependent Response of Staphylococcus aureus to PPArg2‐Based Photodynamic Inactivation

“…In Poland the group of Prof. Graczyk sensitized a new class of protoporphyrin IX amino acid derivatives which as a result of the attachment of two arginines became well soluble in aquatic solutions and possesses amphiphilic character (11,12). Our laboratory has recently demonstrated high effectiveness of porphyrin‐based photoinactivation against methicillin‐resistant S. aureus strains (MRSA; 13), without significant impact on healthy human dermal fibroblasts but having high therapeutic potential in case of human cervical carcinoma and colon carcinoma cells in vitro (14–16). Moreover, we have previously reported that the bactericidal effect of PDT based on protoporphyrin diarginate (PPArg 2 ) sensitizer of S. aureus could be strain‐dependent as effectiveness of PDT ranged from 0 to 3.6 log 10 unit reduction in viable counts (17).…”

“…S1), delivered by the Institute of Optoelectronics, Military University of Technology (Warsaw, Poland) was used as a sensitizer. PPArg 2 was dissolved in distilled water to give a 10 m m stock solution, filtered‐sterilized and stored at a −20°C in darkness until use (13,16,17).…”