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[目的]研究临床分离肠球菌对左氧氟沙星﹑司帕沙星﹑加替沙星等氟喹诺酮类药物(FQNS)的主动外排机制。[方法]用琼脂二倍稀释法测定肠球菌对FQNS的最低抑菌浓度(MIC),同时测定加入主动外排泵抑制剂利血平后肠球菌对FQNS的MIC值。[结果]应用利血平后,肠球菌对3种FQNS的耐药率都降低:左氧氟沙星耐药率从42.0%降至28.6%,司帕沙星耐药率从33.0%降至24.1%,加替沙星耐药率从9.9%降至5.3%;左氧氟沙星MIC90从32mg/L降至16mg/L,司帕沙星MIC50从2mg/L降至1mg/L,MIC90从8mg/L降至4mg/L,加替沙星MIC50从1mg/L降至0.5mg/L,而MIC90从4mg/L降至1mg/L。[结论]主动外排泵抑制剂利血平在体外能降低肠球菌对FQNS的MIC值。
[Objective] To study the active efflux mechanism of enterococci isolated from FQNS by levofloxacin, sparfloxacin, gatifloxacin and so on. [Method] The minimum inhibitory concentration (MIC) of enterococci to FQNS was determined by double dilution method of agar, and the MIC value of Enterococcus faecalis to FQNS with active efflux pump inhibitor reserpine was determined. [Results] After reserpine, the resistance rates of enterococci to the three FQNS strains were reduced: the drug resistance rate of levofloxacin dropped from 42.0% to 28.6%, and the sparfloxacin resistance rate dropped from 33.0% to 24.1% The drug resistance rate of deoxifene was reduced from 9.9% to 5.3%, the MIC90 of levofloxacan was reduced from 32mg / L to 16mg / L, the sparfloxacin MIC50 was reduced from 2mg / L to 1mg / L and the MIC90 was decreased from 8mg / L to 4mg / L, gatifloxacin MIC50 decreased from 1 mg / L to 0.5 mg / L, while MIC90 decreased from 4 mg / L to 1 mg / L. [Conclusion] The active efflux pump inhibitor reserpine can reduce the MIC value of Enterococci to FQNS in vitro.