Cephalosporin antibiotics

A compound selected from a base of the formula ##STR20## wherein Aryl is selected from phenyl and 2-thienyl;

• Y is selected from hydrogen, chlorine, bromine, a straight or branched lower alkyl group of from 1 to 4 carbon atoms and a lower alkoxy group of from 1 to 4 carbon atoms with the proviso that when Aryl is 2-thienyl, Y is hydrogen;
• Z is selected from a bond, oxygen, sulfur and imino with provisio that when Aryl is 2-thienyl, Z is a bond;
• W is selected from hydrogen, methyl, amino, hydroxy, SO.sub.3 H and COOR.sub.1 wherein R.sub.1 is selected from hydrogen and 5-indanyl;
• n is zero, 1 or 2 with the proviso that when W is other than hydrogen or methyl and Z is other than a bond, n is not zero;
• R.sub.2 is selected from hydrogen, and methoxy;
• M is selected from hydrogen;
• a pharmaceutically acceptable non-toxic cation;
• alkanoyloxymethyl wherein the alkanoyl moiety contains from 1 to 5 carbon atoms and may be straight or branched;
• alkanoylaminomethyl wherein the alkanoyl moitety contains from 1 to 5 carbon atoms and may be straight or branched and wherein the amino nitrogen atom may be substituted with an alkyl group of from 1 to 4 carbon atoms;
• alkoxycarbonylaminomethyl wherein the alkoxy moitey contains from 1 to 4 carbon atoms and may be straight or branched and wherein the amino nitrogen atom may be substituted with an alkyl group of from 1 to 4 carbon atoms;
• p-(alkanoyloxy)benzyl wherein the alkanoyl moiety contains from 1 to 5 carbon atoms and may be straight or branched;
• and aminoalkanoyloxymethyl wherein the alkanoyl moiety contains from 2 to 15 carbon atoms and the amino nitrogen may be mono- or di-substituted with a lower alkyl group of from 1 to 4 carbon atoms;
• X is hydrogen or acetoxy;
• and pharmaceutically acceptable salts thereof.