盐酸左氧氟沙星体内外抗菌作用研究

In Vitro and in Vivo Antibacterial Activities of Levofloxacin against Clinic Isolates

目的评价盐酸左氧氟沙星对临床常见致病菌的体内外抗菌活性。方法采用试管二倍稀释法测定最低抑菌浓度(MIC),并对其影响因素进行测定,同时与对照药左氧氟沙星、氧氟沙星进行对比。结果盐酸左氧氟沙星对金黄色葡萄球菌(金葡菌)、表皮葡萄球菌、肺炎球菌等革兰阳性菌有较强的抗菌活性,MIC50为0.16～0.62μg.mL-1;对肠杆菌科细菌如变形杆菌、大肠埃希菌、肺炎克雷白杆菌等革兰阴性菌也有较强的抗菌活性,MIC50为0.31～1.25μg.mL-1;盐酸左氧氟沙星在酸性条件下抗菌活性降低,随着血清浓度及细菌接种量的提高,盐酸左氧氟沙星的MIC值增大2～4倍;盐酸左氧氟沙星对金葡菌、大肠埃希菌感染小鼠有明显的保护作用,其ED50分别为4.54,1.21 mg.kg-1,盐酸左氧氟沙星的作用与左氧氟沙星相似,但明显强于氧氟沙星。结论盐酸左氧氟沙星对临床常见致病菌有良好的抗菌作用。

Objective To evaluate in vitro and in clinical isolates and compare with levofloxacin and ofloxacin . vivo antibacterial activities of levofloxacin hydrochloride against Methods Minimal inhibitory concentration （MIC） tests were carried out using the broth-dilutions methods . The affecting factors were also determined. Drugs were administered intravenously 1 h after mice were infected intraperitoneally with 1 mL of bacterial suspension . The median effective dose （ ED50 ） was calculated by the probit method. Results Levofloxacin hydrochloride had strong activity against gram-positive bacteria , such as staphylococcus aureus , staphylococcus epidermidis and streptococcus pneumoniae with MIC50s 0. 16-0.62μg·mL^-1. It was also active against gram-negative bacteria , such as escherichia coli , proteus and klebsiella pneumoniae with MIC50 s 0. 31- 1.25μg·mL^-1. The antibacterial activity of levofloxacin hydrochloride decreased under acidic condition , increase of serum concentration and bacteria inoculum size . The protective effects of levofloxacin hydrochloride against experimental systemic infections were observed. ED50s of levofloxacin hydrochloride against staphylococcus aureus and escherichia coli were 4.54 and 1. 21 mg · kg^-1 , respectively . Levofloxacin hydrochloride was as active as levofloxacin and was more active than ofloxacin . Conclusion Levofloxacin hydrochloride shows a good activity against clinical isolates , its in vitro antibacterial activities can be changed by pH , serum concentration in culture media and inoculum size .