穿心莲和水飞蓟抑制MRSA41577外排系统的作用机制

Inhibitory effects of andrographis paniculata and silybum marianum on the efflux pump of MRSA 41577

目的研究穿心莲和水飞蓟抑制MRSA41577外排系统的作用机制。方法通过荧光分光光度法检测穿心莲和水飞蓟为MRSA41577外排系统的抑制剂;通过PCR的方法检测MRSA41577的nor A外排基因;通过RT-PCR的方法检测穿心莲和水飞蓟对外排基因nor A表达量的影响。结果穿心莲和水飞蓟处理MRSA41577后,环丙沙星在菌体内的的蓄积量随着药物处理时间的增加而增加,当药物处理菌体12 min后,与对照组相比,菌体内环丙沙星蓄积量分别增加49%和76%(P<0.05),其作用效果优于阳性对照利血平。MRSA41577菌株内含有nor A外排基因。穿心莲和水飞蓟能降低nor A基因表达量,与对照组相比,nor A的相对表达量分别降低了35%和42%(P<0.05)。结论穿心莲和水飞蓟抑制MRSA41577外排系统的作用机制是通过减少nor A外排基因的表达量,进而抑制外排蛋白的合成,阻止药物的外排使菌体重新恢复对药物的敏感性。

Objective To study the inhibitory effects of andrographis paniculata and silybum marianum on the efflux system of MRSA 41577.Methods Inhibitory effects of andrographis paniculata and silybum marianum on efflux system of MRSA 41577 was evaluated using fluorescence spectrophotometry. PCR was applied to detect the nor A efflux gene. By RT-PCR method for detection of andrographis paniculata and silybum marianum influence of the expression of nor A efflux gene. Results Andrographis paniculata and silybum marianum significantly increased the accumulation of ciprofloxacin in MRSA 41577 in a time-dependent manner. At 12 minute,andrographis paniculata and silybum marianum respectively increased ciprofloxacin in MRSA41577 by 49% and 76%（ P〈0. 05）,which is superior to that of reserpine. Further mechanism studies indicated that andrographis paniculata and silybum marianumcould reduce the expression of nor A in MRSA 41577. After incubated with andrographis paniculata and silybum marianum for 16 h, the relative expression of nor A of MRSA41577 was respectively reduced by 35% and 42%（ P〈0. 05）.Conclusion Andrographis paniculata and silybum marianumcould inhibit MRSA efflux system through reducing pathogen ＇s expression of nor A and Nor A protein.