黄芩苷联合左氧氟沙星对铜绿假单胞菌生物膜的影响及相关机制

In vitro activity and related mechanisms of action of baicalin in combination with levofloxacin on Pseudomonas aeruginose biofilms

目的:通过在体外建立铜绿假单孢菌生物膜模型,研究黄芩苷联合左氧氟沙星对黏液型铜绿假单胞菌生物膜的协同杀菌效果并探讨其可能机制。方法:选取临床分离的呼吸道铜绿假单胞菌,采用平板培养法建立体外生物膜模型,连续稀释法分别测定左氧氟沙星和黄芩苷的最低抑菌浓度;采用多功能酶标仪测定左氧氟沙星单独作用以及与黄芩苷联用后生物膜内活菌的荧光强度;采用硫酸-苯酚法检测黄芩苷对藻酸盐含量的影响。结果:当黄芩苷浓度大于5 mg.L-1时,生物膜内活菌数减少(P<0.05);黄芩苷与左氧氟沙星存在协同抗菌作用,随着黄芩苷浓度升高,协同抗菌作用增强(P<0.05或P<0.01);黄芩苷可增强左氧氟沙星对生物膜内藻酸盐含量的降解作用。结论:黄芩苷与左氧氟沙星联用,可显著增强其抗菌活性,降低细菌耐药发生。

OBJECTIVE To investigate the effect of baicalin in combination with levofloxacin on Pseudomonas aeruginosa biofilms and study its possible mechanism of action. METHODS Clinical isolates of Pseudomonas aeruginosa separated from respiratory tract were cultured in plates to establish biofilm formation. Active bacterial counts were determined by serial dilu tion method. The MIC values of baicalin and levofloxacin were measured by doubling dilution methods. The fluorescence inten- sities of mucus-Pseudomonas aeruginose biofilm treated by baicalin, levofloxacin or combined with each other were detected by multi-functional microplate reader. The alginate contents of mucus Pseudomonas aeruginose biofilm were observed by automatic spectrophotometer using sulphuric acid plus phenol method. RESULTS When concentration of baicalin was above 5.0 mg. L 1 , the number of active bacteria in Pseudomonas aeruginose biofilms was decreased significantly （P^0.05）. When levoflox- acin used in coordination with baicalin, they had much better synergistic effects. With the concentration of baicalin increasing, the anti-bacterial effect of levofloxacin increased simutanously （P〈0. 05 or P〈0. 01 ）. On the other hand, baicalin could also improve the degradative effect of levofloxacin on alginate contents in Pseudomonas aeruginose biofilms. CONCLUSION Combi- nation with baicalin, levofloxacin could get much better anti-bacterial ability and thus, maybe decrease the frequencies of bacte rial-resistance.