Antibacterial agents have the formula (I) or are pharmaceutically acceptable salts or in vivo hydrolysable esters thereof: ##STR1## wherein R.sup.3 is phenyl, substituted phenyl, cyclohexenyl, cyclohexadienyl or an optionally substituted 5- or 6-membered heterocyclic ring containing up to three hetero atoms selected from oxygen, sulphur or nitrogen, R.sup.4 is hydrogen or formamido, R.sup.5 is hydrogen, C.sub.1-6 alkyl, substituted alkyl, aryl or aralkyl, R.sup.6 and R.sup.7 are the same or different and represent hydrogen, C.sub.1-6 alkyl, substituted alkyl, halogen, amino, phenyl, substituted phenyl, hydroxyl or C.sub.1-6 alkoxy or R.sup.6 and R.sup.7 form the residue of an optionally substituted 5- or 6-membered carbocyclic ring or a 5- or 6- membered heterocyclic ring containing up to three hetero atoms selected from oxygen, sulphr or nitrogen, and X represents ##STR2## or tautomers thereof wherein R.sup.8 and R.sup.9 are the same or different and each represents hydroxy, or protected hydroxy.
抗菌剂具有公式(I)或其药学上可接受的盐或体内
水解酯:##STR1## 其中R.sup.3是苯基,取代苯基,
环己烯基,环
己二烯基或含有最多三个氧,
硫或氮杂原子的可选取代的5或6元杂环,R.sup.4是氢或甲酰胺基,R.sup.5是氢,C.sub.1-6烷基,取代烷基,芳基或芳基烷基,R.sup.6和R.sup.7相同或不同,代表氢,C.sub.1-6烷基,取代烷基,卤素,
氨基,苯基,取代苯基,羟基或C.sub.1-6烷氧基,或R.sup.6和R.sup.7形成可选取代的5或6元的碳环或含有最多三个氧,
硫或氮杂原子的5或6元杂环的残基,X代表##STR2## 或其互变异构体,其中R.sup.8和R.sup.9相同或不同,每个代表羟基或保护羟基。