Bactericidal activity of Sch 34343 alone and in combination with gentamicin

Sch 34343 inhibited 50% of the 105 bacterial strains tested at concentrations ranging from less than 1.25 to 5.0 mg/l and 90% at 5.0 to 10.0 mg/l. Against Escherichia coli and Klebsiella pneumoniae strains with cefotaxime MICs greater than 5.0 mg/l, 1.0-4.0 mg/l of Sch 34343 was required for inhibition. At concentrations equal to 1 X and 8 X MIC, Sch 34343 rapidly reduced the inoculum by 99% and 99.9%. Against Staphylococcus aureus higher concentrations had a lesser bactericidal activity. Sch 34343 and gentamicin were synergistic at concentrations that were separately subinhibitory.