Comber K R, Boon R J, Sutherland R
Antimicrob Agents Chemother. 1977 Dec;12(6):736-44. doi: 10.1128/AAC.12.6.736.
An experimental mouse intraperitoneal infection due to Escherichia coli was treated with subcutaneous amoxycillin or ampicillin. Specimens of blood and peritoneal washings from the infected animals were assayed for antibiotic concentrations and examined microscopically for observation of the effects produced by the two penicillins on the morphology of bacteria growing in vivo. Amoxycillin was significantly more effective than ampicillin in protecting the animals from the lethal effects of the infection, although the antibiotic concentrations in the body fluids were very similar for both compounds. However, microscopic examination showed marked differences in the morphological effects produced at equivalent dose levels by the two compounds against the bacteria present in blood and peritoneal fluid. Treatment with amoxycillin at dose levels that produced peak antibiotic concentrations in the body fluids ranging from one-quarter to three times the minimum inhibitory concentration resulted in the formation of spheroplast forms, which lysed rapidly. In contrast, at the same concentrations, ampicillin produced relatively stable filaments or long cell forms, which lysed much more slowly, although at higher dose levels the effects produced were generally similar to those seen with amoxycillin. It is concluded that the superior therapeutic activity of amoxycillin compared with ampicillin is due to its greater bacteriolytic activity in vivo.
用皮下注射阿莫西林或氨苄西林治疗实验小鼠因大肠杆菌引起的腹腔感染。对感染动物的血液和腹腔冲洗液样本进行抗生素浓度测定，并进行显微镜检查，以观察两种青霉素对体内生长细菌形态的影响。阿莫西林在保护动物免受感染致死效应方面比氨苄西林显著更有效，尽管两种化合物在体液中的抗生素浓度非常相似。然而，显微镜检查显示，在等效剂量水平下，两种化合物对血液和腹腔液中存在的细菌产生的形态学影响存在显著差异。用阿莫西林治疗，使体液中抗生素峰值浓度达到最低抑菌浓度的四分之一至三倍，导致形成原生质球形式，其迅速裂解。相比之下，在相同浓度下，氨苄西林产生相对稳定的丝状或长细胞形式，其裂解要慢得多，尽管在更高剂量水平下产生的效应通常与阿莫西林所见相似。得出的结论是，阿莫西林与氨苄西林相比具有更好的治疗活性是由于其在体内具有更大的溶菌活性。
