CEPHALOSPORIN DERIVATIVES, PROCESS AND THEIR PREPARATION, AND PROPHYLACTIC AND TREATING AGENT AGAINST BACTERIAL INFECTION

Cephalosporin derivatives represented by the general formula (I), wherein R1 represents an alpha-, beta- or gamma-amino acid residue (bonded through an ester bond) whose amino group is optionally susbstituted by a lower alkyl group, R2 represents a l-alkanoyl-oxyalkyl group, a l-alkoxycarbonyloxyalkyl group, a phthalidyl group or a 5-methyl-1, 3-dioxolen-2-on-4-ylmethyl group, R3 represents a carbamoyloxymethyl group optionally substituted by a lower alkyl group, or a heterocyclic thiomethyl group optionally substituted by a suitable substituent, and R4 represents a hydrogen atom or a hydroxy group, and non-toxic salts thereof are rapidly absorbed in blood by oral administration to exhibit an excellent antibacterial effect, thus useful as an oral prophylactic and treating agent against bacterial infection.