光动力学疗法影响变形链球菌生长和形态的体外研究

目的研究甲苯胺蓝为光敏剂介导的光动力学疗法对变形链球菌体外生长及表面形态的影响,探讨光动力学疗法影响致龋菌生长代谢的作用机制。方法在不同光剂量和不同光敏剂浓度下,通过体外活菌菌落计数法测定光动力学疗法对变形链球菌的生长抑制作用,扫描电镜观察光动力学疗法处理前后菌体表面形态的改变,实验分空白对照组、光敏剂对照组、光对照组和实验组,各组间活菌菌落取对数值后采用析因设计方差分析。结果光动力学疗法能显著抑制变形链球菌的体外生长,随着光照时间和光敏剂浓度的增加,其灭菌效果逐渐增强。当光敏剂浓度为100μg/ml,光照时间为5、15、25 min时,细菌菌落对数值分别为(7.40±0.13)、(6.86±0.14)、(6.44±0.28),与空白对照组(8.30±0.04)相比差异有显著性(P<0.05),5 min与15 min两实验组之间差异有显著性(P<0.01)。光敏剂浓度和光剂量二因素之间存在交互作用(F=19.47,P<0.01)。扫描电镜观察显示实验组变形链球菌与对照组相比菌体表面粗糙不平,有水泡状凸起。结论甲苯胺蓝为光敏剂介导的光动力学疗法能显著抑制变形链球菌体外生长并改变其表面形态。

Photodynamic therapy on viability and morphology of Streptococcus mutans in vitro

Objective To evaluate the impact of photodynamic therapy on the viability and morphology of Streptococcus mutans in a planktonic culture.Methods Inhibitory action of toluidine blue O-mediated photodynamic therapy on Streptococcus mutans were analyzed by colony-counting method under different light intensity in vitro.Cell morphologic changes of Streptococcus mutans was observed under scanning electron microscope.Samples were prepared and divided into control group,photosensitizer control group,light control group and photodynamic therapy group.Results Photodynamic therapy resulted in a significant reduction in the bacterial growth in a irradiation time-and photosensitizer concentration-dependent manner.When the photosensitizer concentration was 100 μg/ml,irradiation time of 5,15 and 25 min had colony log value of Streptococcus mutans for 7.40±0.13,6.86±0.14,and 6.44±0.28 respectively,which were significant lower than control group(8.30±0.04,P<0.05).Interaction was found between photosensitizer concentration and the light dosage(F=19.47,P<0.01).Scanning electron microscopy displayed that the bacterial cell surfaces of photodynamic therapy group became rough,with blister shaped bulge.Conclusion Photodynamic therapy with toluidine blue O as photosensitizer exerts efficient inhibitory effect on the growth and morphology of Streptococcus mutans.