药敏试验 E test 法与琼脂扩散法的方法学比较

Comparison of a new antimicrobial susceptibility test,E test with disk diffusion

介绍一种新的药敏试验Ｅｔｅｓｔ（ＡＢＢｉｏｄｉｓｋ，Ｓｏｌｎａ，Ｓｗｅｄｅｎ）法，并与常用的纸片扩散法进行比较。Ｅｔｅｓｔ法系利用琼脂扩散法的原理，把一载有抗生素连续指数梯度浓度的５×５０ｍｍ的塑料条放于已接种菌液的琼脂板上，此条包含１５个ｌｏｇ２的稀释倍数，从抑菌环与载体条交界处可定量读出ＭＩＣ值。分别用Ｅｔｅｓｔ和纸片扩散法测定了临床分离的３１０株革兰氏阴性杆菌对１０种抗生素的敏感性。结果显示Ｅｔｅｓｔ与纸片扩散法的一致性达９０．１％，相关性在０．７５～０．９３之间，平均为０．８７，以Ｅｔｅｓｔ法为标准计算纸片扩散法的平均极大误差为１．５％，大误差为２．６％。结论认为Ｅｔｅｓｔ是一种精确可靠的药敏方法；常规纸片扩散法必须严格按照标准化进行。

Objectives to introduce a new technique for antimicrobial susceptibility testing,Etest(AB Biodisk,Solna,Sweden),and compare it with routine disk diffusion method.Methods Etest uses diffusion principle,and places a plastic strip(5 by 50mm) with a continuous concentration antimicrobic gradient on inoculated agar plate.The strip has 15 twofold dilution,and MICs are read where the edge of the inhibition zone intersects the strip.We compared the Etest with disk diffusion by using clinically isolated 310 strains to 10 antimicrobial agents.Results The Etest category agreement with disk diffusion was 90.1%,the correlation coefficient was 0.87,ranged from 0.75 to 0.93.As the Etest was standard,the very major error of disk diffusion was 1.5%,the major error was 2.6%.Conclusions Etest was a accurate and reliable method for antimicrobial susceptibility testing,through it some problems were found in routine antimicrobial susceptibility test.