In vitro-activity of clavulanic acid and amoxicillin combined against amoxicillin-resistant bacteria

The ability of clavulanic acid to inactivate β-lactamase was investigated using 47 amoxicillin-resistant bacteria. In the presence of 10 mg/l clavulanic acid most strains of staphylococci,Escherichia coli, Klebsiella andProteus mirabilis became fully amoxicillinsensitive. This effect of clavulanic acid was in most instances not observed withSerratia marcescens, Proteus inconstans, Pseudomonas aeruginosa, Enterobacter and indole-positiveProteus species.