以微生物擴散分析法檢測抗生素力價

Determination of Antibiotic Potency With Microbial Diffusion Assay

以微生物擴散分析法檢測抗生素力價時受使用菌株種類、菌株形態、檢測方式、培養基用量和標準液配置法等影響。當以Bacillus cereus var. mycoides ATCC 11778 和 B. subtilis ATCC 6633 為測定菌株時，芽胞懸浮液比營養菌體敏感，而以紙錠法或不銹鋼圓筒檢測時其準確度間無顯著性差異。分析盤培養基的厚度對準確度影響不大，但以緩衝液配製抗生素標準溶液時比直接用蒸餾水配製時為佳。在固態基質中，隨著抗生素濃度之增加，如以生物檢測時，其回收率增加，但如以高效液相層析法測定時則影響不大。以高效液相層析法、分光光譜法和微生物檢測法所能檢測地靈黴素之最低濃度分別為1.00, 0.10 和 0.01μg/ml。可見以微生物擴散分析法檢測抗生素之方法既簡便且靈敏。

The sensitivity of microbial diffusion assay for antibiotic potency was affected by test organism, cell stage, assay medium volume and preparation of standard sample. Bacillus cereus var. mycoides ATCC 11778 was more sensitive than B. Subtilis ATCC 6633 in oxytetracycline determination. The optimal conditions for microbial diffusion assay of oxytetracycline were the spore suspension of B. cereus var. mycoidcs ATCC 11778, with paper disc method (or stainless steel cyclinder method), 200 ml of assay medium and preparation antibiotic solution with phosphate buffer. Antibiotics recovery from the solid substrate increased with the amount of antibiotics. The minimal concentration of oxytetracycline could be detected by microbial diffusion assay, UV-spectrometry, and HPLC method was 0.01, 0.10, and 1.00µg ml-1, respectively.