【摘要】 目的 深入研究肠球菌耐药性的产生机制，指导临床合理用药。 方法 采用一步诱导法，对8株粪肠球菌、2株屎肠球菌和9株粪肠球菌、1株屎肠球菌进行四环素和左氧氟沙星诱导性耐药试验。对诱导出的菌株用琼脂稀释法测定药物敏感性;用PCR法检测四环素耐药基因tetM、tetL，用PCR法扩增gyrA、parC基因后测定DNA序列。 结果 10株实验菌中的2株诱导产生了多株稳定的四环素耐药株。耐药株的MIC分别为16～128μg/ml，与原株MIC0.25μg/ml、2μg/ml)比较，增加了16～512倍。在1株实验菌的诱导耐药株的质粒DNA上检测到tetL耐药基因，另一株实验菌株的诱导耐药株的染色体DNA上检测到tetM耐药基因;10株实验菌中的2株诱导产生了多株稳定的左氧氟沙星耐药株。诱导耐药株的MIC分别为16～64μg/ml，与原株(MIC2μg/ml、2μg/ml)比较，增加了8～32倍。GyrA的QRDR内的第87位或第83位的氨基酸及ParC的QRDR内的第80位的氨基酸均发生了改变。 结论 一步法抗菌药物诱导性耐药试验的结果表明，肠球菌可在高于耐药MIC浓度的抗菌药物短期作用后获得耐药性。

    【关键词】 肠球菌 抗菌药物 诱导性耐药 抗菌药物压力

    Laboratory study of antibacterial agents on enterococcus induced resistance

    Liu Guijian，Xu Shuzhen

    Microbiology Laboratory，Beijing Friendship Hospital Affiliated to Capital Medical University，Beijing100050.

    【Abstract】 Objective The purpose of the present research was to study on the emergence mechanism of ente-rococcal resistance to a variety of antibacterial agents，and to guide the selection and use of antimicrobial agents in clinical practice.Methods Eight of faecalis enterococcus and two of faecalis enterococcus，nine of faecalis enterococ-cus and one of faecium enterococcus were selected to performed experiments on induced resistance to tetracycline、lev-ofloxacin respectively by one-step method.The susceptibility of the induced strains resisitant to tetracycline、lev-ofloxacin was measured by determining the MIC using agar dilution method.The tetM and tetL gene in the induced strains were detected by PCR ......