左氧氟沙星、环丙沙星单用和联合其他抗菌药物对铜绿假单胞菌防突变浓度的研究

目的了解左氧氟沙星、环丙沙星单用及其与头孢他啶、美罗培南、阿米卡星联合使用，对铜绿假单胞菌防突变浓度（MPC）的变化。方法采用琼脂稀释法测定上述抗菌药物单用及联合使用对8株左氧氟沙星、环丙沙星敏感铜绿假单胞菌的MPC，并计算耐药频率。结果左氧氟沙星、环丙沙星单用对上述8株铜绿假单胞菌MPC／MIC分别为8～32、8～16；两药分别与头孢他啶、美罗培南和阿米卡星联合使用，MPC／MIC则降为2～8、2～4、1～2、1～2、4～8和1～8，联合用药较单独用药MPC／MIC下降2～16倍，且其耐药频率也大幅下降。结论联合用药能使耐药突变选择窗变窄，使MPC／MIC降低，减少耐药菌产生。

Study on mutant prevention concentrations of levofloxacin,ciprofloxacin alone and in combination with the other antimicrobial agents against Pseudomonas aeruginosa

Objective To evaluate the mutant prevention concentrations(MPC)of levofloxacin,ciprofloxacin alone and in combination with ceftazidime,meropenem and amikacin against Pseudomonas aeruginosa.Methods MPC of the above drugs for 8 strains of levofloxacin and ciprofloxacin-susceptible Pseudomonas aeruginosa were detected with agar dilution method,antimicrobial-resistant frequencies were calculated.Results The MPC/MIC ratios of levofloxacin and ciprofloxacin alone for 8 strains of Pseudomonas aeruginosa were 8~32 and 8~16 respectively,and MPC/MIC ratios of the combination application with ceftazidime,meropenem and amikacin for Pseudomonas aeruginosa were 2~8,2~4,1~2,1~2,4~8 and 1~8 respectively,the ratios for the combination application decreased two to sixteen-fold,drug-resistant frequencies were also lower than the single application of levofloxacin and ciprofloxacin.Conclusion Combination use of antimicrobial agents can narrow the mutant selection window and reduce the MPC/MIC,so the emergence of resistant strains are decreased.