硝酸镓对尿路致病性大肠埃希菌及其生物膜的抑制作用

Inhibitory activity of gallium nitrate against uropathogenic Escherichia coli and their biofilm formation

目的检测新型抗菌剂硝酸镓对临床分离的尿路致病性大肠埃希菌(UPEC)及其生物膜的抑制作用,探索清除细菌生物膜的新方法。方法采用微量肉汤稀释法和结晶紫染色法分别测定硝酸镓对10株UPEC的最低抑菌浓度(MIC)和生物膜的抑制率,同时观察铁离子(Fe^(3+))对硝酸镓抑菌作用的影响,用以分析硝酸镓的抗菌机制。结果硝酸镓对试验菌株的MIC为10～12 mg/L,对早期生物膜的抑制率为88.5%～92.7%,各菌株间差异无统计意义(P>0.05),高浓度的Fe^(3+)能够降低硝酸镓的抑菌作用。结论硝酸镓通过与Fe^(3+)竞争,限制细菌对铁的摄取和利用从而抑制细菌生长,表现出较强的抗菌作用,对尿路感染的防治有待进一步研究。

Objective To investigate the inhibitory effects of gallium nitrate against 10 strains of uropathogenic Escherichia coli （UPEC） and their biofilm formation. Methods The broth microdilution and crystal violet stain were used respectively for measuring the minimum inhibitory concentration （MIC） and the inhibition rate of biofilm formation. The Fe3＋ was added to the me- dium to analyze the bacteriostatic mechanisms of gallium nitrate. Results The MICs were 10-12 mg/L for the strains tested. The inhibition rates of early biofilms were 88.5 % to 92.7 %. The effects of gallium nitrate showed no statistical difference a mong the 10 strains （P〉0.05）. The high level of Fe3＋ attenuated the inhibitory activity of gallium nitrate. Conclusions Gall um （Ga3＋ ） exhibits strong inhibitory effect on planktonic and adherent UPEC strains through competing with the microorganisms for the utilization of Fe3＋ so as to limit the growth of bacteria, which warrants further research for the potential role of gallium nitrate in the prevention and control of urinary tract infections.