亚抑菌浓度庆大霉素对铜绿假单胞菌的影响

Effet of sub-minimal inhibitory concentration of Gentamycin on Pseudomonas aeruginosa

目的探讨亚抑菌浓度庆大霉素(GEN)对铜绿假单胞菌(PAO1)浮游菌和生物膜的影响。方法采用微量肉汤稀释法检测PAO1对GEN的敏感性。采用96孔板比浊法检测亚抑菌浓度GEN对PAO1浮游菌生长的影响,并通过结晶紫染色法检测亚抑菌浓度GEN对PAO1生物膜形成的影响。采用化学反应比色法测定亚抑菌浓度GEN对PAO1毒力因子表达的影响。结果 GEN对PAO1的最低抑菌浓度为2μg/ml;而当GEN浓度≤0.250μg/ml时,不影响PAO1浮游菌的增殖;当GEN为0.125μg/ml时,能促进PAO1生物膜的形成(P<0.05),且在一定范围内(0.125~0.250μg/ml)随着GEN浓度增高,其促进生物膜形成的能力越强;0.125和0.250μg/ml GEN能促进群体密度信号系统相关基因las I、las R、rhl I、rhl R、pqs C、pqs D和毒力因子青脓素、弹性蛋白酶、碱性蛋白酶的表达(P<0.05),且呈一定的剂量依赖性。结论亚抑菌浓度GEN在一定浓度范围内能促进PAO1生物膜的形成,并进一步促进群体密度信号系统相关基因和毒力因子的表达。

Objective To study the effect of Gentamycin of sub-minimal inhibitory concentration(sub-MIC)on Pseudomonas aeruginosa. Methods Microdilution method was used to detect the sensitivity of P. aeruginosa to Gentamycin. And the turbidity method was used to check the effect of sub-MIC of Gentamycin on the growth of P. aeruginosa planktonic bacteria. Then, crystal violet method was used to explore the effect of sub-MIC Gentamycin on the biofilm formation of P. aeruginosa. Finally, chemical colorimetric method was utilized to test the effect of sub-MIC Gentamycin on the virulence factor production of P. aeruginosa. Results The MIC of Gentamycin on P. aeruginosa was 2 μg/ml. Gentamycin ≤0.250 μg/ml had no influence on the growth of planktonic bacteria. Gentamycin could significantly enhance the biofilm formation at the concentration of 0.125-0.250 μg/ml and in a dose-dependent manner(P < 0.05). At the same time, 0.125 and0.250 μg/ml Gentamycin could significantly promote the expressions of the quorum sensing system(QS) related genes las I, las R, rhl I, rhl R, pqs C and pqs D, and the virulence factors pyocyanin, elastase and alkaline protease in a dose-dependent manner(P < 0.05). Conclusions sub-MIC Gentamycin could enhance the biofilm formation and the expressions of QS related genes and virulence factors.