Abstract: New cephalosporin derivatives of a general formula (I) and non-toxic salts and non-toxic esters thereof are provided: ##STR1## (wherein R represents an acyclic or cyclic lower alkyl group having 1-6 carbon atoms, which may optionally be substituted by a halogen atom; the steric configuration as asterisked (*) includes an optical-active (R)-form or (S)-form or an optical-inactive (RS)-form; n is 0 or 1, n.sup.1 is 0 to 3, n.sup.2 is 0 to 3; and when n.sup.1 is 0, n.sup.2 is 3; when n.sup.1 is 1, n.sup.2 is 2; when n.sup.1 is 2, n.sup.2 is 1; when n.sup.1 is 3, n.sup.2 is 0).The new derivatives of the formula (I) and non-toxic salts and esters thereof have high bactericidal activity with broad antibacterial spectra, and these are useful as active ingredients in bactericides.

Abstract: A class of new caphalosporin compounds (syn-isomer) is now provided, which is useful as antibacterial agent and is represented by the general formula (I) ##STR1## wherein R.sup.1 is an amino group or a protected amino group; R.sup.2 is a lower alkyl group, a carboxymethyl group or a protected carboxymethyl group; R.sup.3 is a hydrogen atom, a salt-forming cation or a carboxyl-protecting group; A is an unsubstituted or substituted phenyl group, an unsubstituted or substituted furyl group, an unsubstituted or substituted thiazolyl group or an unsubstituted or substituted 3-lower-alkylthiazolio group, and a pharmaceutically acceptable salt or ester thereof.