多重耐药泵抑制剂提高肠球菌对氟喹诺酮药物敏感性的研究

目的　研究临床分离肠球菌对诺氟沙星、环丙沙星、氧氟沙星等氟喹诺酮药物耐药的主动泵出机制。方法　收集临床分离肠球菌 ;用琼脂二倍稀释法测定多重耐药泵抑制剂利舍平或维拉帕米应用前后 ,菌株对氟喹诺酮药物 MIC的变化。结果　利舍平使所有被检测的 2 9株肠球菌对诺氟沙星的敏感性增加 (MIC下降至原值的 1/ 2或以下 ) ,使 2 3株肠球菌对环丙沙星的敏感性增加 ,但仅能增加 3株肠球菌对氧氟沙星的敏感性。应用利舍平以后 ,12株耐诺氟沙星粪肠球菌对诺氟沙星 MIC值均下降 ,11株耐环丙沙星粪肠球菌有7株对环丙沙星 MIC值下降。维拉帕米的抑制效果和利舍平相比略有差异。结论　诺氟沙星、环丙沙星的主动泵出机制普遍存在于临床分离肠球菌 ,并且是粪肠球菌对诺氟沙星、环丙沙星的耐药机制之一。

Effect of multidrug resistance efflux pump inhibitor on susceptibility to fluoroquinolones in clinical isolates of Entrococci

Objective To investigate the efflux-mediated resistance to fluoroquinolones in clinical isolates of Enterococci . Methods To collect 29 clinical isolates of Entrococci including 25 of Enterococcus faecalis ,1 of Enterococcus faecium,Enterococcus casseliflavus,Enterococcus avium and Enterococcus hirae ,respectively. Their susceptibilities to norfloxacin,ciprofloxacin and ofloxacin in the presence or absence of multidrug resistance efflux pump inhibitor reserpine or verapamil were determined by an agar dilution method. Result The susceptibilities of all isolates to norfloxacin and 23 of isolates to ciprofloxacin showed increases in the presence of reserpine,while only 3 isolates increased in their susceptibilities to ofloxacin in the presence of reserpine. The susceptibilities of all 12 norfloxacin resistant Enterococcus faecalis to norfloxacin and 7 of 11 ciprofloxacin resistant Enterococcus faecalis to ciprofloxacin showed increases in the presence of reserpine. The effects of verapamil and reserpine were similar. Conclusions Active export of norfloxacin or ciprofloxacin is prevalent in clinical isolates of Entrococci and efflux mechanism is a cause of clinically fluoroquinolone resistance in Entrococci .