利奈唑胺的体外抗菌作用研究

目的评价抗菌新药利奈唑胺的体外抗菌作用。方法采用琼脂对倍稀释法测定利奈唑胺对579株临床分离菌的体外抗菌活性，并与有关抗菌药进行比较；测定利奈唑胺的杀菌浓度和杀菌曲线；培养条件对利奈唑胺抗菌活性的影响。结果利奈唑胺对葡萄球菌属、肺炎链球菌等链球菌属、肠球菌属临床分离菌均具高度抗菌活性，包括对其中的甲氧西林耐药葡萄球菌、青霉素中介肺炎链球菌亦具良好的抗菌作用。对流感嗜血杆菌、淋病奈瑟菌的抗菌活性较低。对脆弱拟杆菌等厌氧菌具较高抗菌活性。利奈唑胺对耐药的革兰阳性球菌的抗菌作用与万古霉素和替考拉宁相仿或略强。最低杀菌浓度（MBC）测定及杀菌曲线试验结果显示利奈唑胺对肺炎链球菌、溶血性链球菌具有很强的杀菌作用，对大部分葡萄球菌属具杀菌作用，对肠球菌仅具抑菌作用。培养基pH值的改变、细菌接种量的改变对利奈唑胺抗菌活性有一定影响，人血清含量改变对该药抗菌活性无明显影响。结论利奈唑胺对需氧革兰阳性球菌，包括多重耐药菌具有高度抗菌活性，且与其他抗菌药问无交叉耐药。提示利奈唑胺对革兰阳性球菌，尤其是多重耐药株所致感染的控制将具有重要作用。

In vitro activities of linezolid against clinical isolates

Objective To evaluate the in vitro activity of linezolid. Methods The minimum inhibitory concentrations （MICs） of linezolid against 579 strains of recent clinical isolates were determined and compared with selected eomparators by means of agar dilution. The minimum bactericidal concentrations （MBCs） and time-kill curve of linezolid were determined. The effects of culture conditions on activity of linezolid were determined. Results Linezolid was highly active against gram-positive cocci, including methieillin-resistant Staphylococcus spp. , penicillin-intermediate S. pneurnoniae, E. faecalis and E. faecium. However, it was poorly active against H. influenzae and N. gonorrhoeae. Linezolid was highly active against anaerobes, such as B. fragilis, Peptostreptococcus spp. and P. acnes. It was as active as or slightly more active than vaneomycin and teieoplanin in the activity against resistant aerobic gram-positive cocci. Linezolid was an excellent bactericidal agent against S. pneumoniae and hemolytic Streptococcus. And it was also bactericidal against most Staphylococci, but inhibitory for Enterococcus spp. The change of culture conditions, including pH of medium and inoeulum size, had some effects on the activity of linezolid, whereas the concentration of human serum in broth had no effect on the activity of linezolid. Conclusions The excellent in vitro activity against multiply resistant gram-positive microorganisms and the absence of cross-resistance with other antimierobial agents make linezolid a promising new drug. Linezolid seems to have an important role in combating infections caused by gram-positive cocci, especially resistant isolates.