GR-20263: a NewAminothiazolyl Cephalosporin withHigh Activity Against Pseudomonas andEnterobacteriaceae

and5to20 times more active thancefuroxime, cefoxitin, andcephalothin. GR-20263 was three tosixtimes less active thancefotaxime against Escherichia coli, Klebsiella pneumoniae, Salmonella, andShigella, butthree tofourtimes more active than cefotaxime against Proteus vulgaris andSerratia marcescens.Theactivity of GR-20263 against Pseudomonas aeruginosa (with miniimal inhibitory concentra- tions of2and8,g/mlfor90and100%oftheisolates, respectively) was similar to thatoftobramycin, 2times thatofcefsulodin, 5times thatofpiperacillin, and10 timesthatofcefotaxime. Against Haemophilus influenzae GR-20263 was three times more active thanampicillin. Thebeta-lactamase-producing strains were as