左氧氟沙星对兔组织笼金黄色葡萄球菌感染的疗效研究

目的：建立兔组织笼感染模型并观察左氧氟沙星对金黄色葡萄球菌感染的剂量反应关系。方法：在兔背部皮下植入1个无菌高尔夫练习球，待球内充满组织液后，往球内注入金黄色葡萄球菌，建立组织笼感染模型。然后分别给予不同剂量的左氧氟沙星灌胃治疗，抽取组织液测定细菌浓度及耐药性的变化。结果：5mg／kg治疗组在治疗过程中细菌浓度降低，治疗结束后细菌恢复生长；10mg／kg和20mg／kg组在治疗后细菌浓度迅速降低，并在治疗过程中细菌恢复生长；而40mg／kg组在治疗过程中细菌浓度迅速降低，在治疗结束后细菌仍未恢复生长。5、10、20mg／kg治疗组都较容易发生耐药，而40mg／kg治疗组无1例耐药发生。结论：金黄色葡萄球菌对左氧氟沙星治疗的反应和耐药的发生依赖于左氧氟沙星的剂量。

Development of tissue cage infection model and study of efficacy of levofloxacin in treatment of staphylococcus aureus infection

AIM: To develop tissue cage infection model and study the efficacy of levofloxacin in treatment of staphylococcus aureus infection. METHODS: A plastic ball was implanted into each rabbit through a dorsal midline incision under aseptic conditions. By 4 weeks after implantation, each plastic ball had filled with clear, yellowish tissue fluid. To develop tissue cage infection model, staphylococcus aureus culture was injected into each preimplanted plastic ball. Rabbits were administered levofloxacin at different dose once daily by use of a gavage feeding tube. Tissue cage fluid was taken out from the plastic ball, and concentration of bacteria and loss of susceptibility were monitored in tissue cage fluid. RESULTS: Levofloxacin at 5 mg/kg caused bacterial numbers to decrease throughout treatment. Doses of levofloxacin at 10 or 20 mg/kg reduced bacterial numbers for the first 3 days, but bacterial growth was observed during late stage of treatment and during post-treatment observation. Levofloxacin at 40 mg/kg caused bacterial numbers to decrease throughout treatment and to remain low level during the growth recovery period. Dose of levofloxacin at 5 or 10 or 20 mg/kg caused the loss of susceptibility easily, but no resistance occurred at dose of 40 mg/kg. CONCLUSION: The bacterial response and occurrence of resistance depend on the levofloxacin dose.