大肠杆菌体内氟喹诺酮类药物耐药机制的研究

目的研究临床分离的大肠杆菌敏感株和多重耐药菌株体内的氟喹诺酮类药物积聚情况与耐药性的关系。方法采用荧光测定法测定亲水性和疏水性氟喹诺酮类药物在临床分离的大肠杆菌敏感株及多重耐药株菌体内的蓄积量及葡萄糖与能量抑制剂氰氯苯腙(CCCP)对氟喹诺酮类药物在菌体内蓄积量的影响。结果大肠杆菌敏感株和多重耐药菌株内的氟喹诺酮类药物蓄积浓度呈能量依赖性降低，以多重耐药株菌内的蓄积浓度下降最明显。加入能量抑制剂后，多重耐药株菌内的亲水性氟喹诺酮类药物蓄积浓度上升近3倍；而疏水性氟喹诺酮类药物妥舒沙星的稳态蓄积浓度明显低于亲水性氟喹诺酮类药物蓄积量的上升幅度。结论能量依赖的主动泵出可能是大肠杆菌对其耐药机制之一，蓄积量减少导致的耐药在亲水性氟喹诺酮类药物中更为重要。

Study on the Accumulation of Fluoroquinolones in Clinical Isolates of Susceptible and Multi-drug-resistant Escherichia coli Strains

Objective To investigate the active efflux of fluoroquinolones in clinical isolated strains of Escherichia coli. Methods The accumulation of ciprofloxacin and tosufloxacin for clinical isolates of Escherichia coli and the effect of glucose and Carbonyl cyanide mchlorophenyl hydrazone (CCCP)on the uptake of Escherichia coli were determined by a modified fluorometric assay. Results The accumulation of ciprofloxacin in sensitive and multi-drug-resistant(MDR)organisms decreased with energy dependence, and the decrease in MDR isolate was prominent. Incubation with CCCP increased the accumulation of ciprofloxacin up to three-fold in MDR isolate but not in sensitive isolate. In contrast,CCCP appeared to have no influence on the uptake of tosufloxacin in Escherichia coli. Conclusion These results indicate that energy-dependent active efflux is one of the mechanisms of hydrophilic fluoroquinolones resistance, but it does not play any role in hydrophobic fluoroquinolones resistance in Escherichia coli.