An antibacterial agent is provided which is a cephem compound of the formula: ##STR1## wherein R.sup.1 is an acyl group; R.sup.2 is a carboxy group which may be esterified; R.sup.3 is a hydrogen atom, a lower alkyl group or cyano group; R.sup.4 is a hydrogen atom or a lower alkyl group, or R.sup.4 together with R.sup.3 is a methylene chain having 2 or 3 carbon atoms; R.sup.5 is a hydrogen atom or a lower alkyl group; A is an optionally substituted bivalent aromatic heterocyclic group which is bonded to a ring-constituting carbon atom with the adjacent sulfur atom; Y is a binding arm, sulfur or oxygen atom, --NH--, --CONH-- or --NHCO--; Z is a binding bond or --NH--; m is an integer of 0 to 4 and n is an integer of 0 to 6, or a pharmacologically acceptable salt thereof.
提供一种抗菌剂,其为式为:##STR1##的头孢烯化合物,其中R.sup.1为酰基;R.sup.2为羧基,可以酯化;R.sup.3为氢原子、较低的烷基或
氰基;R.sup.4为氢原子或较低的烷基,或者R.sup.4和R.sup.3一起是具有2或3个碳原子的亚甲基链;R.sup.5为氢原子或较低的烷基;A为可选择取代的双价芳香杂环基团,与相邻的
硫原子的环构成碳原子键合;Y为结合臂、
硫或氧原子、--NH--、--CONH--或--NHCO--;Z为结合键或--NH--;m为0到4的整数,n为0到6的整数,或其药学上可接受的盐。