CEPHALOSPORIN ANTIBIOTICS

摘要

Cephalosporin antibiotics of the general formula (I) (wherein Ra and Rb, which may be the same or different, each represent a C1-4 alkyl group or Ra and Rb together with the carbon atom to which they are attached form a C3-7 cycloalkylidene group; and R4 represents hydrogen or a 3- or 4-carbamoyl group with the proviso that Ra and Rb do not each represent a methyl group when R4 represents hydrogen) exhibit broad spectrum antibiotic activity, the activity being unusually high against gram-negative organisms such as strains of Pseudomonas organisms. The invention also includes the non-toxic salts and non-toxic metabolically labile esters of compounds of formula (I). Also described are compositions containing the antibiotics of the invention and processes for the preparation of such antibiotics.