In vitro photodynamic inactivation of bacterial isolates from wound by 5-aminolevulinic acid

• Main Authors: Chun-Ta Yeh, 葉駿達
• Other Authors: Lien-I Hor
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/96216052773360160739

碩士 === 國立成功大學 === 微生物及免疫學研究所 === 96 === 　　Photodynamic therapy （PDT） combines the photosensitizers （PSs） and visible light to produce a phototoxic response that results in oxidative damages to a variety of targets including nucleic acids, proteins, and lipids. It has been noticed that bacterial strains of the same species were repeatedly isolated from the wounds of two patients who received one and five, respectively, courses of PDT with 5-aminolevulinic acid （ALA）, a precursor of photoactive porphyrin derivatives. From one of them the oxacillin-resistant Staphylococcus aureus （ORSA）, Enterococcus faecalis and Shewanella putrefaciens were isolated, while from the other patient only Pseudomonas aeruginosa was isolated. The strains of each species exhibited at least two different randomly amplified polymorphic DNA （RAPD） types. We then examined the strains of different RAPD types for their susceptibility to photodynamic inactivation（PDI） with ALA and the amount of porphyrins produced in their cells. We found that strains of ORSA and P. aeruginosa could be killed by ALA-PDI but those of E. faecalis and S. putrefaciens could not. Both the susceptibility to ALA-PDI and amounts of porphyrins synthesized from ALA showed a dose-dependent response for the P. aeruginosa strains. Strains of ORSA showed an optimal response to 0.1 mM of ALA for both the sensitivity to ALA-PDI and porphyrins production from ALA. No fluorescence representing the porphyrins produced from ALA was detected in E. faecalis, suggesting that this species may be unable to uptake or metabolize ALA to porphyrins, which leads to irresponsiveness of this bacterial species to ALA-PDI. Intriguingly, although strong fluorescence signals were detected in the cells of S. putrefaciens, strains of this species were resistant to ALA-PDI. These results suggest that the bacterial pathogens may not be equally sensitive to PDT with ALA, and it may be necessary to test each isolate to find the optimal ALA-PDT conditions.