Novel cephalosporins of the formula, ##STR1## wherein R is a hydrogen atom or an alkyl, aryl or thienyl group, and R' is a group which constitutes together with the adjacent nitrogen atom a 5- or 6-membered ring containing 1 or 2 nitrogen atoms, which are effective particularly against Pseudomonas aeruginosa as well as against other Gram negative and positive microorganisms, for example, N-[7-(.alpha.-sulfophenylacetamido)ceph-3-em-3-ylmethyl] pyridinium 4-carboxylate, N-[7-(.alpha.-sulfo-3'-thienylacetamido)ceph-3-em-3-ylmethyl] pyridinium-4-carboxylate, and their pharmaceutically acceptable salts thereof. Sodium salt of the former is prepared by, e.g. reacting sodium 7-(.alpha.-sulfophenylacetamido) cephalosporanate with pyridine in water.
Synthesis and in vitro activity of a number of cephalosporins having α-sulfoacyl- or other acyl groups, e.g., α-carboxyacyl- and α-sulfoaminoacyl- at the 7-position and bearing a variety of heterocyclic thioether or pyridinium moieties at the 3-position are described.
A method of combating bacterial infections in humans involves the administration of an antibacterially effective amount of a compound of the formula: ##STR1## wherein R is phenyl or thienyl group, and R' is a group which constitutes together with the adjacent nitrogen atom a pyridinium group that is unsubstituted or substituted by carbamoyl, or a 4'-methyl-5'-(.beta.-hydroxyethyl)-thiazolium or a pharmaceutically acceptable salt thereof, to a patient. This method is effective particularly against Pseudomonas aeruginosa as well as against other Gram negative and positive microorganisms.