Propenyl cephalosporin derivatives

Disclosed are cephalosporin derivatives of the general formulawherein R is an organic residue with a molecular weight not exceeding 400 bonded to the adjacent sulphur atom via carbon and consisting of carbon, hydrogen, and optional oxygen, sulfur, nitrogen and/or halogen atoms; R1 is hydrogen, lower alkyl or phenyl; and A is a secondary, tertiary or quaternary nitrogen atom bound directly to the propenyl group and being substituted by an organic residue with a molecular weight not exceeding 400 and consisting of carbon, hydrogen, and optional oxygen, sulfur, nitrogen and/or halogen atoms,as well as readily hydrolyzable esters thereof, pharmaceutically acceptable salts of said compounds and hydrates of the compounds of formula I and of their esters and salts.