Cephem compounds and composition

摘要

This invention relates to novel cephem compounds of high antimicrobial activity of the formula: <IMAGE> wherein R1 is amino or protected amino, A is lower alkylene which may be substituted with oxo, hydroxy, amino, protected hydroxy or protected amino, R2 is hydrogen, halogen or hydroxy, and R3 is carboxy or functionally modified carboxy, its nontoxic, pharmaceutically acceptable salt and a bioprecursor thereof.