Post-antibiotic effect of Amoxicillin nanoparticles against main pathogenic bacteria of Bovine mastitis in vitro | 阿莫西林纳米粒对奶牛乳房炎主要病原菌的体外PAE

Chinese. 研究阿莫西林纳米粒（AMX-NP）对奶牛乳房炎主要病原菌金黄色葡萄球菌标准株ATCC25923及其临床分离株、无乳链球菌、大肠杆菌标准株ATCC25922及其临床分离株的体外抗菌后效应（PAE）。制备AMX-NP，试管二倍稀释法测定其对乳房炎主要病原菌的最小抑菌浓度（MIC）和最小杀菌浓度（MBC）。采用细菌显微镜直接计数法，于AMX-NP PAE期的不同时间点分别测定其在0.5×MIC、1×MIC、2×MIC和4×MIC时的体外PAE。当AMX-NP质量浓度分别为0.5×MIC、1×MIC、2×MIC和4×MIC时，其对乳房炎主要病原菌均产生一定的PAE，PAE值与AMX-NP质量浓度（0.5×MIC～4×MIC）呈剂量依赖性，且该药物对金黄色葡萄球菌和无乳链球菌产生的PAE值均较大肠杆菌长。临床应用AMX-NP防治奶牛乳房炎时，对于金黄色葡萄球菌性和无乳链球菌性乳房炎，可适当延长给药间隔时间，对于大肠杆菌性乳房炎，宜缩短给药间隔或持续给药。

English. The post-antibiotic effect (PAE) of Amoxicillin nanoparticles（AMX-NP）against pathogenic bacteria of bovine mastitis in vitro was studied. These bacteria mainly included S. aureus ATCC25923 and its isolates from veterinary clinic, S. agalactiae, E. coli ATCC25922 and its isolates from veterinary clinic. The minimal inhibitory concentration (MIC) and the minimal bactericidal concentration (MBC) of AMX-NP against these pathogenic bacteria were measured by tube double dilution method after the preparation of AMX-NP. By the microscope direct counting method of the bacteria the PAE of AMX-NP against every bacterium was determined at the concentration of 0.5×MIC, 1×MIC, 2×MIC and 4×MIC respectively during the PAE of AMX-NP. At the concentration of 0.5×MIC, 1×MIC, 2×MIC and 4×MIC the marked PAE was all found when AMX-NP were used. The value of PAE was enhanced with the increasing concentration, showing strongly concentration-dependent, and the value of PAE against S. aureus and S. agalactiae was higher than that of PAE against E. coli. Longer dosing interval should be recommended when AMX-NP were used for the prevention and cure of bovine mastitis by S. aureus and S. agalactiae. However, shortened dosing interval or successive dosing should be taken when they were used against sensitive E. coli.