多重耐药大肠杆菌中的主动外排机制

目的研究主动外排系统在多重耐药大肠杆菌中的作用。方法用抽滤法测定了３Ｈ四环素和３Ｈ青霉素在临床分离的大肠杆菌中的积聚。结果在临床分离的多重耐药大肠杆菌中四环素和青霉素稳态浓度均显著低于敏感株；供能时稳态浓度明显下降，给予能量抑制剂后细胞内药物浓度则又显著上升，而敏感株变化不明显。ＬＭ３１３．１（大肠杆菌野生株ＡＧ１００经诱导产生的多重耐药株）对四环素的积聚及对ＣＣＣＰ的反应与临床分离多重耐药株一致，而ＬＭ３１３．５（ＬＭ３１３．１经噬菌体将Ｔｎ５插入ｍａｒＡ并使之失活的突变株）与临床分离的敏感株一致。结论多重耐药大肠杆菌中存在四环素和青霉素的主动外排系统。主动外排系统是其形成多重耐药的机制之一。

Active efflux of tetracycline and penicillin in multiple antibiotic resistant (Mar) Escherichia coli

Objective To investigate the active efflux system of antibiotics in multiple antibiotic resistant (Mar) Escherichia coli. Methods The accumulation of 3H tetracycline and 3H penicillin were determined using filtration method.Results The steady concentration of drugs in Mar strains of Escherichia coli were significantly lower than those in susceptible strains. Moreover, in Mar strains, the steady concentration significantly decreased with energy supply and remarkably increased with inhibition of energy supply; however, in the susceptible strain, the change was not significant. In LM313.1 (Mar mutant of wild strain AG100), the accumulation of tetracycline and penicillin was similar to clinical Mar strains, while in LM313.5(marA in LM313.1 inactived by insertion of Tn5), the accumulation of tetracycline and penicillin was similar to susceptibile isolates.Conclusion There are active efflux pump(s) of tetracycline and penicillin in Mar Escherichia coli, which plays an important role in multiple antibiotic resistance.