Effects of 5-aminolevulinic acid-based photodynamic therapy on Staphylococcus epidermidis biofilms
10.3760/cma.j.issn.0412-4030.2012.12.010
- VernacularTitle:氨基酮戊酸光动力对表皮葡萄球菌生物膜作用
- Author:
Xin LI
;
Hongwei WANG
;
Xiuli WANG
- Publication Type:Journal Article
- Keywords:
Aminolevulinic acid;
Photochemotherapy;
Biofilms;
Staphylococcus epidermidis
- From:
Chinese Journal of Dermatology
2012;(12):865-869
- CountryChina
- Language:Chinese
-
Abstract:
Objective To evaluate the effect of 5-aminolevulinic acid-based photodynamic therapy (ALA-PDT) on S.epidermidis biofilms.Methods S.epidermidis was cultured on cover glasses,with or without thepresence of ALA at 50 mmol/L for 16 hours followed by the exposure to different doses (100,200,300 J/cm2) of red light.S.epidermidis receiving neither pretreatment nor irradiation served as the negative control.Subsequently,confocal laser scanning microscopy (CLSM) was used to observe the structure and evaluate the biological activity of S.epidermidis biofilms; colony forming units (CFUs) of S.epidermidis were counted for the evaluation of killing effect of ALA-PDT; scanning electron microscopy (SEM) was used to observe the morphological structure of the biofilms.Results The number of colony forming units per milliliter (CFU/ml) was (210 ± 7.55) × 105,(91 ± 1.53) × 105,(16 ± 1.52) × 105 for S.epidermidis pretreated with ALA followed by irradiation with red light at 100,200 and 300 J/cm2 respectively,significantly different from untreated S.epidermidis ((388 ±8.89) × 105,all P ＜ 0.01) and S.epidermidis irradiated with red light only.Increased ratio of dead to live cells was observed in ALA-pretreated S.epidermidis irradiated with red light at 100,200 and 300 J/cm2compared with untreated S.epidermidis (1.254 ± 0.096,1.301 ± 0.160 and 3.410 ± 1.140 vs.0.358 ± 0.057,all P ＜ 0.01) and S.epidermidis irradiated with red light only.SEM showed that the biofilm structure was loose and obscure in S.epidermidis treated with ALA-PDT,and even disappeared with S.epidermidis distributed in single colonies when the dose of red light was 300 mJ/cm2.Conclusion ALA-PDT shows a potential bactericidal activity against S.epidermidis in biofilms,which can not only reduce biofilm vitality,but also damage biofilm structure.
