Summary of Antibiotic Inactivation Studies for Gram-positive Isolates.

Strains were grown in 50% TSB for 5 days in presence of 20 µg/ml antibiotic. Conditional media was used for setting up disk diffusion assays and LC-MS analyses. Inactivation was defined as the absence of a zone of clearance around the disk. Hydrolytic mechanism of ß-lactam resistance is inferred.

菌株置于含20 µg/ml抗生素的50%胰蛋白胨大豆肉汤（Tryptic Soy Broth, TSB）中培养5天。采用条件培养基构建纸片扩散法试验体系并开展液相色谱-质谱联用（Liquid Chromatography-Mass Spectrometry, LC-MS）分析。将纸片周围未出现抑菌圈定义为抗生素发生灭活。据此可推断出β-内酰胺（ß-lactam）耐药的水解作用机制。