ABSTRACT
AIM: Conventional disinfection techniques, considered safe for plasma, are usually associated with collateral damages on concentrated platelets and erythrocytes. Alternative methods are required and antimicrobial photodynamic therapy (aPDT) seems promising. In this study the effectiveness of two photosensitizers (PS), a porphyrin and a phthalocyanine, to disinfect blood products was evaluated. RESULTS: The cationic porphyrin was more effective in the photoinactivation of bacteria. Also, no significant osmotic stress was found for samples treated with PS at 5.0 µM in isotonic conditions after antimicrobial photodynamic therapy. CONCLUSION: Effective reduction of Gram-positive bacteria at 5.0 µM of PS provided promising indications toward its safe use to disinfect blood samples. For Gram-negative bacteria, lower PS concentrations, between 5.0 and 10 µM, must be tested.
Subject(s)
Blood Safety , Blood/microbiology , Disinfection , Escherichia coli/drug effects , Photosensitizing Agents/pharmacology , Staphylococcus aureus/drug effects , Erythrocytes/drug effects , Humans , Indoles/pharmacology , Isoindoles , Light , Plasma/microbiology , Porphyrins/pharmacologyABSTRACT
BACKGROUND: Photodynamic inactivation of micro-organisms is a promising nonantibiotic multitarget approach to treat localized and superficial infections through oxidative stress. Herein, the changes occurring on major cellular components of Escherichia coli and Staphylococcus warneri, induced by photosensitization with cationic porphyrins (Tri-Py(+)-Me-PF and Tetra-Py(+)-Me) and white light, were monitored by infrared spectroscopy. RESULTS: In E. coli, most of the changes occurred on proteins and lipids, suggesting a key effect on lipopolysaccharides in the first irradiation times. In S. warneri, proteins were the major molecular targets of oxidative damage but phospholipids and polysaccharides were also affected. CONCLUSION: Infrared spectroscopy is a very interesting tool to monitor biochemical changes induced by photosensitization in bacteria and also to infer on its mechanism of action.
Subject(s)
Escherichia coli/drug effects , Light , Photosensitizing Agents/pharmacology , Porphyrins/pharmacology , Staphylococcus/drug effects , Cations , Escherichia coli/metabolism , Escherichia coli/radiation effects , Oxidation-Reduction , Phospholipids/metabolism , Polysaccharides, Bacterial/metabolism , Spectrophotometry, Infrared , Staphylococcus/metabolism , Staphylococcus/radiation effectsABSTRACT
The emergence of microbial resistance is becoming a global problem in clinical and environmental areas. As such, the development of drugs with novel modes of action will be vital to meet the threats created by the rise in microbial resistance. Microbial photodynamic inactivation is receiving considerable attention for its potentialities as a new antimicrobial treatment. This review addresses the interactions between photosensitizers and bacterial cells (binding site and cellular localization), the ultrastructural, morphological and functional changes observed at initial stages and during the course of photodynamic inactivation, the oxidative alterations in specific molecular targets, and a possible development of resistance.
