In vitro activity of the novel cephalosporin GR69153

The in vitro activity of GR69153 was compared to that of ceftazidime, ceftriaxone, imipenem and gentamicin against a total of 702 recent clinical isolates. MICs were determined by a standard agar dilution procedure and two inocula (10(4) and 10(8) cfu) were used throughout. GR69153 inhibited 90% of isolates of Escherichia coli, Klebsiella pneumonia and Proteus mirabilis at less than or equal to 0.25 mg/l and 90% of isolates of Pseudomonas aeruginosa at less than or equal to 1 mg/l. Citrobacter freundii (MIC90 16 mg/l), Morganella morganii (MIC90 128 mg/l) and Enterobacter spp. (MIC90 greater than 128 mg/l) were considerably more resistant to GR69153. GR69153 was four-fold more active than ceftazidime against methicillin-sensitive Staphylococcus aureus but was inactive against methicillin-resistant Staphylococcus aureus, Enterococcus faecalis and Bacteroides fragilis group.