自从50年前发现青霉素以来,在世界范围内曾花费了巨大的努力集中在β-内酰胺抗生素的研究和开发方面。但直至1970年仅仅发现了二类天然的β-内酰胺抗生素,即青霉素和头孢菌素类。近几年由于新的筛选方法和分离技术的出现,逐渐发现了各种类型的含有β-内酰胺环的抗生素,如1971年 Na-garajan 等报道了7α-甲氧头孢菌素(即所谓头霉素),这类抗生素不仅具较广的抗菌谱,而且对β-内酰胺酶非常稳定。1976年 Howarth Ever since penicillin was discovered 50 years ago, great efforts have been spent worldwide on the research and development of beta-lactam antibiotics. However, only a second class of natural beta-lactam antibiotics, penicillins and cephalosporins, were discovered until 1970. In recent years, due to the emergence of new screening methods and separation techniques, various types of antibiotics containing β-lactam rings have been gradually discovered. For example, Na-garajan et al. Reported in 1971 that 7α-methoxycephalosporins Mycophenolate), these antibiotics not only has a broader antibacterial spectrum, but also very stable for β-lactamase. Howarth, 1976