不同配比的他唑巴坦与头孢噻肟对β内酰胺酶的稳定性

Stability of different ratios from matching cefotaxime and tazobactam

目的研究不同配比他唑巴坦(β内酰胺酶抑制剂)与头孢噻肟(第3代头孢类抗生素)复方制剂的体外抑酶率。方法从超声破碎细菌得粗制β内酰胺酶,用平皿二倍稀释法测定MIC值,测定临床分离菌31株的细菌敏感性,用生物法测定酶水解率,计算酶对底物水解率,以头孢噻肟水解率为100%,计算不同配比的抑酶保护率。结果头孢噻肟/他唑巴坦1∶1与3∶1组的酶水解率比较无明显差别(P>0.05),3种配比(1∶1),(5∶1),(7∶1)的酶水解率比较都有差别(P<0.01)。结论头孢噻肟/他唑巴坦(1∶1,3∶1)抑酶率明显高于其他配比,建议用3∶1配方,以降低酶抑制剂的使用量。

Objective To study the inhibition rate of different formula- tions of cefotaxime/tazobactam on extended spectrum β - lactamases. Methods Bacterial susceptibility testing was performed on 31 clinical isolates. Minimal inhibitory concentrations （MIC） were determined by use of Agar dilution method. The inhibitory activities of different ratios cefotaxime and tazobactam against β -lactamases were detected by using bioassay. Results The inhibitory activities of cefotaxime/tazobactam with 1 ： 1 and 3 ： 1 ratios to β - lactamases were similar （ P 〉 0.05 ） . There were significant difference among the inhibitory rate of eefotaxime/ tazobactam with 1：1 ratio and with 5：1 and 7：1 ratios on β -lactamases （ P 〈 0.01 ）. Conclusion The inhibitory rates on β - lactamases of cefotaxime/tazobactam with 1：1 and 3：1 ratios were significantly higher than those of the other ratios. Three： one is the best ratio due to decreasing the dose of enzyme inhibitor - tazobactam.