微生物法测定妥布霉素效价的方法改进

利用抗生素在琼脂培养基内的扩散作用,采用量反应平行原理,比较妥布霉素等氨基甙类抗生素标准品与供试品两者对接种的实验菌产生抑菌圈的大小,以测定供试品效价。为了改善妥布霉素抑菌圈的清晰度及大小,提高实验结果的灵敏度与重现性,在pH值为7.8的磷酸盐缓冲液中加入氯化钠,使缓冲液中氯化钠的质量浓度为20g/L,则抑菌圈的直径增大,清晰度提高,用抗生素效价测量仪测量,实验结果的可信限率降低,误差减小。

Improvement of Microbiological Efficacy-cost Measurement of Tobramycin

The potency of an antibiotics such as tobramycin is determined by Microbiological Efficacy-cost. Antibiotics can diffuse in agar plate.A plot can be obtained between the different concentration of antibiotics reference and the related agar plate ring dimensions .After measuring the agar plate ring dimension of the antibiotic,the related concentration can be obtained according to the above-mentioned plot.In order to improve the definition and size of tobramycin's bacteriostatic circle and increase the sensitivity and repeatability of the result,a given concentration of 20 g/L of NaCl should be added into the pH 7.8 phosphate buffer solution.As a result the circle's diameter is enlarged and the definition is improved.Therefore,the confidence limit rate and error of the experimental result is reduced when the solution is measured by antibiotic efficacy-cost assay apparatus.