不同配比头孢呋辛与他唑巴坦的体外抗菌活性

In vitro antibacterial activities of different ratios from matching cefuroxime/tazobactam against clinical isolates

目的评价不同配比头孢呋辛／他唑巴坦及单剂对临床分离致病菌的体外抗菌活性。方法以平皿二倍稀释法对22种661株致病菌测定MIC值；以试管二倍稀释法测定MBC值；以活菌计数法绘制杀菌曲线。结果661株致病菌中，72．01％产β内酰胺酶；联合制剂明显增强了对革兰阴性菌的抗菌作用；酶抑制剂他唑巴坦可明显提高头孢呋辛对耐药菌的抗菌作用，MIC90值下降到单药的1／8～1／30，耐药率减少了12％～80％。在碱性条件下，使联合制剂抗菌作用增强；而酸性环境，可减弱其抗菌作用；4个配比中，1：1配比抗菌作用最强。结论头孢呋辛／他唑巴坦（1：1）为一强效广谱杀菌药。

Objective To study the in vitro activity of cefuroxime alone and cefuroxime/tazobactam combined at various ratios （ 1 ： 1,2： 1,4： 1, 8：1 ）against clinical isolates. Methods Minimal inhibitory concentration（MIC） were determined by the twofold agar dilution and minimal bactericidal concentration （MBC） were determined by the twofold broth dilution method. Bactericidal curve was draw. Results MIC of cefuroxime/tazobactam against 661 clinical isolates （ with 72.01% β- lactam producing） of 22 strains, which were isolated from 15 hospitals in 10 different areas in China between January 2001 and January 2003, were measured. The in vitro activity against gram - negative bacilli was significantly enhanced by combined use of cefumxime/tazobactam, especially to Esche- richia coli, Klebsiella spp. , Proteus spp., Morganella morganii , Enterobacter cloacae, and Citrobacter freundii. The inducing of tazobactam has significantly enhanced the antibacterial activities of cefuroxime ,which the MICgodecreased to 1/8 ～ 1/30 of the original level, drug resistance rate reduced 12% -80%. The combination use of cefumxime/tazobactam showed excellent anti - bacilli activity except to methicilline recietant Staphylococcus aureus and showed excellent bactericidal activity. MIC was unaffected by inoculum size and there was little variations affected by the concentration of human serum. The activity of cefuroxime/tazobactam against Escherichia coli and Klebsiella pneumoniae increased in alkalescence condition and decreased in the acidic environment. The best antibacterial activity of cefumxime/tazobactam was achieved in the ratio of 1 ： 1. Conclusion The combination of cefuroximc/tazobactam （ 1 ： 1 ） is an excellent bactericidal medicine.