氨苄西林与阿莫西林对金黄色葡萄球菌及大肠杆菌的体外抗菌后效应

Postantibiotic effect of ampicillin and amoxycillin on Staphylococcus aureus and Escherichia coli in vitro

采用菌落计数法分别测定了氨苄西林和阿莫西林在 0 5、 1、 2、 4倍于各菌最小抑菌浓度 (MIC)时对金黄色葡萄球菌、大肠杆菌标准株及其临床分离株的体外抗生素后效应 (PAE)。结果显示 ,氨苄西林和阿莫西林在 0 5、 1、 2、 4倍MIC时对金黄色葡萄球菌C2 61 1 2 及临床分离株均具有一定的PAE ,且PAE与浓度在一定范围内 (0 5～ 4倍MIC)呈剂量依赖性 ,当药物浓度达 4倍MIC时 ,PAE明显延长 (P <0 0 5 ) ;但两药对金黄色葡萄球菌C2 61 1 2 及临床分离株的PAE值仅在4倍MIC时差异显著 (P <0 0 5 )。在相同浓度下 ,两药对大肠杆菌ATCC2 5 92 2和临床分离株的PAE很小甚至没有。提示 :在临床设计给药方案时 ,对金黄色葡萄球菌敏感株引起的感染 ,除了考虑药代动力学和MIC指标外 ,还应考虑PAE因素 ,可适当延长给药间隔时间 ;而对PAE无意义的大肠杆菌敏感株引起的感染 。

The postantibiotic effect(PAE)of ampicillin and amoxycillin on Staphylococcus aureus and Escherichia coli in vitro was studied.Dilution method was used for the drugs removal and Muelle Hinton agar colony counting method was used to monitored the growth of bacteria.The results showed that marked PAE was found even in the subinhibitory concentration(sub MIC)when ampicillin and amoxycillin were used against S.aureus C 26112 and the isolate obtained from veterinary clinic at concentration of 0 5,1,2,4×MIC.The duration of PAE was enhanced with the increasing concentration,showing strongly a concentration dependent,especially at 4×MIC,the PAE was obvirously prolonged (P <0 05).Negative PAE was defined,when the two drugs were used against E coli at the same concentration.It suggested that longer dosing interval should be recommended when the two drugs used against S aureus ,however,successive dosing or shorted dosing interval should be taken when they used against sensitive E coli .