Abstract: 7 .alpha.-formamido cephalosporin derivatives having a 3[N-(optionally substituted)aminothiopyridinium thiomethyl] substituent have anti-bacterial activity and are of use in anti-bacterial therapy. Processes for the preparation thereof and intermediates for use in these processes are also disclosed.

Abstract: .beta.-Lactam antibiotics have the formula (Ia) or are pharmaceutically acceptable salts or pharmaceutically acceptable in vivo hydrolysable esters thereof: ##STR1## in which the group CO.sub.2 R.sup.1 is carboxy or a carboxylate anion. The use of the compounds and processes for their preparation are disclosed.

Abstract: .beta.-Lactam antibiotics are disclosed which have the formulae (Ia) or pharmaceutically acceptable salts or pharmaceutically acceptable in vivo hydrolysable esters thereof: ##STR1## wherein R.sup.1 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.2 is hydrogen or optionally substituted C.sub.1-6 alkyl; R.sup.3 is an optionally substituted 5- or 6- membered heterocyclic group containing one or two nitrogen heteroatoms; or R.sup.2 and R.sup.3 together with the nitrogen atom to which they are attached form an optionally substituted 5- or 6- membered heterocyclic group contaning one or two nitrogen heteroatoms; R.sup.4 is a substituted pyridinium group; and CO.sub.2 R is carboxy or a carboxylate anion; and also the use thereof.Processes for the preparation of the compounds are disclosed together with intermediates for use therein.

Abstract: A monocyclic .beta.-lactam antibiotic having a formamido substituent at the 3S-position, including compounds of the formula (I): ##STR1## and salts thereof wherein R is --SO.sub.3 H; --PO(OH)Y wherein Y is C.sub.1-6 alkoxy, hydroxy, aryloxy, C.sub.1-6 alkyl or aryl; ##STR2## wherein Z represents C.sub.1-6 alkyl or aryl; ##STR3## wherein Z.sup.1 and Z.sup.2 may be the same or different and each represents hydrogen, C.sub.1-6 alkyl, aryl, amino or C.sub.1-6 alkoxy, or Z.sup.1 and Z.sup.2 together form the residue of a heterocyclic ring; --OSO.sub.3 H; or ##STR4## where X is hydrogen or hydroxy; R.sup.1 is an amino, protected amino or carboxylic acylamino group, and R.sup.2 and R.sup.3 are independently selected from hydrogen or a hydrocarbon group of 1 to 18 carbon atoms.

Abstract: A monocyclic .beta.-lactam antibiotic having a formamido substitutent at the 3S-position, including compounds of the formula (I): ##STR1## and salts thereof wherein R is --SO.sub.3 H; --PO(OH)Y wherein Y is C.sub.1-6 alkoxy, hydroxy, aryloxy, C.sub.1-6 alkyl or aryl; ##STR2## wherein Z represents C.sub.1-6 alkyl or aryl; ##STR3## wherein Z.sup.1 and Z.sup.2 may be the same or different and each represents hydrogen, C.sub.1-6 alkyl, aryl, amino or C.sub.1-6 alkoxy, or Z.sup.1 and Z.sup.2 together form the residue of a heterocyclic ring; --OSO.sub.3 H; or ##STR4## where X is hydrogen or hydroxy; R.sup.1 is an amino, protected amino or carboxylic acylamino group, and R.sup.2 and R.sup.3 are independently selected from hydrogen or a hydrocarbon group of 1 to 18 carbon atoms.

Abstract: A monocyclic .beta.-lactam antibiotic having a formamido substituent at the 3S-position, including compounds of the formula (I): ##STR1## and salts thereof wherein R is --SO.sub.3 H; --PO(OH)Y wherein Y is C.sub.1-6 alkoxy, hydroxy, aryloxy, C.sub.1-6 alkyl or aryl; ##STR2## wherein Z represents C.sub.1-6 alkyl or aryl; ##STR3## wherein Z.sup.1 and Z.sup.2 may be the same or different and each represents hydrogen, C.sub.1-6 alkyl, aryl, amino or C.sub.1-6 alkoxy, or Z.sup.1 and Z.sup.2 together form the residue of a heterocyclic ring; --OSO.sub.3 H; or ##STR4## where X is hydrogen or hydroxy; R.sup.1 is an amino, protected amino or carboxylic acylamino group, and R.sup.2 and R.sup.3 are independently selected from hydrogen or a hydrocarbon group of 1 to 18 carbon atoms.