Abstract: Cephalosporin antibiotics of general formula: ##STR1## (wherein R.sup.a and R.sup.b, which may be the same or different, each represent a C.sub.1-4 alkyl group or R.sup.a and R.sup.b together with the carbon atom to which they are attached form a C.sub.3-7 cycloalkylidene group, and Y.sup..sym. represents a C-linked 5- or 6-membered heterocyclic ring containing at least one C.sub.1-4 alkyl-substituted quaternary nitrogen atom, which ring may also contain one or more sulphur atoms) exhibit broad spectrum antibiotic activity, the activity being unusually high against gram-negative organisms such as strains of Pseudomonas organisms.A particular antibiotic compound of formula (I) possessing excellent antibacterial activity against strains of Pseudomonas organisms, as well as other valuable therapeutic properties, is (6R,7R)-7-[(Z)-2-(2-aminothiazol-4-yl)-2-(1-carboxycyclobut-1-oxyimino)ace tamido]-3-[(1-methylpyridinium-4-yl)-thiomethyl]ceph-3-em-4-carboxylate.

Abstract: Cephalosporin antibiotics of the general formula ##STR1## (wherein R.sup.a and R.sup.b, which may be the same or different, each represent a C.sub.1-4 alkyl group or R.sup.a and R.sup.b together with the carbon atom to which they are attached form a C.sub.3-7 cycloalkylidene group; and R.sup.4 represents hydrogen or a 3- or 4-carbamoyl group) exhibit broad spectrum antibiotic activity, the activity being unusually high against gram-negative organisms such as strains of Pseudomonas organisms. A particular antibiotic compound of formula (I) possessing excellent antibacterial activity against strains of Pseudomonas organisms, as well as other valuable therapeutic properties, is (6R,7R)-7-[(Z)-2-(2-aminothiazol-4-yl)-2-(2-carboxyprop-2-oxyimino) acetamido]-3-(1-pyridiniummethyl)-ceph-3-em-4 carboxylate. The invention also includes the non-toxic salts and non-toxic metabolically labile esters of compounds of formula (I).

Abstract: Cephalosporin antibiotics of general formula ##STR1## (wherein Y.sup..sym. represents a C-attached 1-C.sub.1-4 alkylpyridinium group) exhibit broad spectrum antibiotic activity with unusually high activity against strains of Pseudomonas organisms as well as high activity against various members of the Enterobacteriaceae. The invention also includes the non-toxic salts, non-toxic metabolically labile esters and 1-oxides of compounds of formula (I). Also described are compositions containing the antibiotics of the invention and processes for the preparation of the antibiotics.

Abstract: Cephalosporin antibiotics of general formula ##STR1## (wherein R.sup.a and R.sup.b, which may be the same or different, each represent a C.sub.1-4 alkyl group, or together with the carbon atom to which they are attached form a C.sub.3-7 cycloalkylidene group and R.sup.1 represents a C.sub.1-4 alkyl group) exhibit broad spectrum antibiotic activity, the activity being unusually high against gram-negative organisms such as strains of Pseudomonas organisms.Particularly effective compounds of formula (I) are (6R,7R)-7-[(Z)-2-(2-aminothiazol-4-yl)-2-(2-carboxyprop-2-oxyimino)acetami do]-3-(2-methylpyrazolium-1-ylmethyl)ceph-3-em-4-carboxylate and (6R,7R)-7-[(Z)-2-(2-aminothiazol-4-yl)-2-[(1-carboxycyclobut-1-oxyimino)ac etamido]-3-(2-methylpyrazolium-1-ylmethyl)]ceph-3-em-4-carboxylate.

Abstract: Cephalosporin antibiotics of general formula ##STR1## (wherein R.sup.a and R.sup.b, which may be the same or different, each represent a C.sub.1-4 alkyl group, or together with the carbon atom to which they are attached form a C.sub.3-7 cycloalkylidene group). These compounds exhibit broad spectrum antibiotic activity, the activity being unusually high against gram-negative organisms such as strains of Pseudomonas organisms.Particularly effective compounds of formula (I) are (6R,7R)-7-[(Z)-2-(2-aminothiazol-4-yl)-2-(2-carboxyprop-2-oxyimino)acetami o]-3-(pyridazinium-1-ylmethyl)ceph-3-em-4-carboxylate and (6R,7R)-7-[(Z)-2-(2-aminothiazol-4-yl)-2-(t-carboxycyclobut-1-oxyimino)ace tamido]-3-(pyridazinium-1-ylmethyl)ceph-3-em-4-carboxylate. The invention also includes the non-toxic salts and non-toxic metabolically labile esters of compounds of formula (I), compositions containing the antibiotic compounds of the invention and a method of combatting bacterial infection utilizing the antibiotics.

Abstract: Compounds of the general formula ##STR1## (wherein R represents a methyl or 2-chloroethyl group and * represents an asymmetric carbon atom). The above compounds are useful as orally administrable antibiotics.

Abstract: Cephalosporin antibiotics of the general formula ##STR1## (wherein R.sup.a and R.sup.b, which may be the same or different, each represent a C.sub.1-4 alkyl group or R.sup.a and R.sup.b together with the carbon atom to which they are attached form a C.sub.3-7 cycloalkylidene group; and R.sup.4 represents hydrogen or a 3- or 4-carbamoyl group) exhibit broad spectrum antibiotic activity, the activity being unusually high against gram-negative organisms such as strains of Pseudomonas organisms. A particular antibiotic compound of formula (I) possessing excellent antibacterial activity against strains of Pseudomonas organisms, as well as other valuable therapeutic properties, is (6R,7R)-7-[(Z)-2-(2-aminothiazol-4-yl)-2-(2-carboxyprop-2-oxyimono) acetamido]-3-(1-pyridiniummethyl)-ceph-3-em-4 carboxylate. The invention also includes the non-toxic salts and non-toxic metabolically labile esters of compounds of formula (I).