Bactericidal activity of cefodizime on Enterobacteriaceae in an in-vitro model simulating plasma pharmacokinetics in humans.

An in-vitro dialysis model was employed to assess the feasibility of once-daily dosing of cefodizime in the treatment of infections caused by various Enterobacteriaceae: Escherichia coli, Klebsiella pneumoniae , Morganella morganii, Serratia marcescens, Providencia stuartii and Enterobacter cloacae. This model simulated the concentrations of cefodizime detected in human blood after an intravenous (iv) bolus injection of 1 g or 2 g of the antibiotic. Validation of the model was undertaken to confirm its utility. Based on the data obtained with this model, once-daily dosing with 1 g cefodizime (iv) should be effective against infections due to the commonest Gram-negative bacteria (E. coli , K. pneumoniae , M. morganii ). For infections caused by Enterobacteri aceae strains that produce large quantities of Class I -lactamases, twice-daily (P. stuartii or S. marcescens) or four times daily (E. cloacae) administration of 1 g cefodizime may be required.