The in-vitro activity of ceftibuten against 475 clinical isolates of Gram-negative bacilli, compared with cefuroxime and cefadroxil

Abstract

The in-vitro activity of ceftibuten was compared with cefuroxime and cefadroxil against 475 clinically-significant, epidemiologically-distinct isolates of Gram-negative bacilli: 170 from blood, 212 from urine and 93 from a supplementary collection of multiply-resistant strains known to have resistance plasmids, to have caused sporadic or epidemic nosocomial infection, or both. Ceftibuten MICs ranged from 0.003 to greater than 32 mg/l, with a modal MIC of 0.01 mg/l: 95% of all isolates had ceftibuten MIC values of less than or equal to 8 mg/l, the sensitivity breakpoint suggested by the manufacturer. Ninety per cent of isolates had MICs of less than or equal to 1 mg/l and 49% had MICs of less than or equal to 0.03 mg/l. All isolates of Klebsiella, Serratia, Proteus and Providencia spp., and Morganella morganii had MIC values of 8 mg/l or less. Only two of 124 isolates of Escherichia coli tested, and only one of 23 Citrobacter spp., had MICs of greater than 8 mg/l (16, 16 and greater than 32 mg/l respectively). Resistance MIC greater than 16 mg/l) was more frequent among Enterobacter and Acinetobacter spp. Thirteen of 52 Enterobacter spp., and seven of 18 Acinetobacter calcoaceticus had MICs of at least 32 mg/l. MIC ranges, modal MICs and MIC90s indicated that ceftibuten was, with the exception of only two strains, consistently more active in-vitro than cefuroxime, which was in turn more active than cefadroxil.