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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。
Objective To study the role of active efflux system in multidrug-resistant Escherichia coli. Methods The concentration of 3H-tetracycline and 3H-penicillin in clinically isolated E. coli was determined by suction filtration. Results The steady-state concentrations of tetracycline and penicillin in clinical isolates of multidrug-resistant Escherichia coli were significantly lower than those of the sensitive strains. The steady-state concentration decreased significantly when the energy was supplied, and the intracellular drug concentration was significantly increased after the energy-depressant was administered. However, Change is not obvious. The accumulation of tetracycline and response to CCCP in LM313.1 (multi-drug resistant strain induced by E. coli wild strain AG100) was consistent with clinical isolates of multidrug-resistant strains, whereas LM313.5 (LM313.1 by phage inserted Tn5 into marA And inactivate the mutants) with the clinical isolates of the sensitive strains. Conclusion The active efflux system of tetracycline and penicillin exists in multidrug-resistant Escherichia coli. Active efflux system is one of the mechanisms of multi-drug resistance.