ACYLAMINO-CEPHEM-CARBOXYLIC ACIDS

Acylamino-cephem-carboxylic acids of the general formula IN WHICH R1, R2 and R3 represent hydrogen or lower alkyl groups and R1 and R2 may form together an alkylene group which may be substituted, R4 represents a linear or branched alkyl radical of 1 to 5 carbon atoms, a cyclo-alkyl radical of 3 to 7 carbon atoms which may be interrupted by heteroatoms, X represents a single bond or NH, A represents a phenylene or thienylene group which may be substituted and Y represents a single bond or oxygen, and their physiologically tolerated salts; the novel compounds have very good anti-bacterial properties.