| 摘要 |
Cephalosporin antibiotics having the formula: <IMAGE> (where R is thienyl, furyl or phenyl; Ra is hydrogen, C1-4 alkyl, C2-4 alkenyl, C3-7 cycloalkyl or phenyl, and Rb is hydrogen, C1-4 alkyl, C2-4 alkenyl, C3-7 cycloalkyl, phenyl, carboxy or C2-5 alkoxycarbonyl, or Ra and Rb together with the carbon atom to which they are attached form a C3-7 cycloalkylidene or cycloalkenylidene group: and Y is the residue of a nitrogen nucleophile and their physiologically acceptable derivatives exhibit broad spectrum antibiotic activity characterized by particularly high activity against gram negative microorganisms, including those which produce beta -lactamases. The compounds, which are syn isomers or exist as mixtures of syn and anti isomers containing at least 90% of the syn isomer, have particularly high in vitro activity against strains of Escherichia coli, Haemophilus influenzae and Proteus organisms; and unusually high activity against Pseudomonas organisms.
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