Killing kinetics of five orally administered antibiotics at clinically achievable concentrations against moraxella catarrhalis.

Time-kill kinetic studies were used to measure the bactericidal activity of amoxicillin/clavulanic acid (in a new form for pediatric use), cefaclor, cefuroxime, cefixime and erythromycin against 30 beta-lactamase producing Moraxella catarrhalis strains. Antibiotics were tested at the mean maximum serum concentration observed after administration of a standard dose and at 0.5 × Cmax, 0.33 × Cmax and 0.25 × Cmax. A 2 log10 reduction in colony counts was obtained with the Cmax of amoxicillin/clavulanic acid and cefixime after 5 h of incubation. After 24 h of incubation a decrease of 3 and 4 log was observed with cefixime and amoxicillin/clavulanic acid respectively. At 0.5 × Cmax and 0.33 × Cmax, bactericidal activity was obtained only with amoxicillin/clavulanic acid. [ABSTRACT FROM AUTHOR]