In vitro antibacterial properties of cefetamet and in vivo activity of its orally absorbable ester derivative, cefetamet pivoxil

Abstract

The in vitro activity of cefetamet, the microbiologically active metabolite of the orally administered prodrug cefetamet pivoxil, was compared with that of cephalexin, cefaclor, cefuroxime and amoxicillin. Cefetamet was highly active againstEnterobacteriaceae, Neisseria spp.,Vibrio spp.,Haemophilus influenzae and streptococci other than enterococci. Cefetamet inhibited cefaclor-resistant species such asProteus vulgaris, Providencia stuartii, Providencia rettgeri andSerratia marcescens. Staphylococci,Pseudomonas aeruginosa and cephalosporinase-overproducing strains ofEnterobacter cloacae were resistant to cefetamet. The superior activity of cefetamet compared with older oral beta-lactam antibiotics against a large number of gram-negative pathogens correlated with enhanced stability towards betalactamases. In accordance with the in vitro findings, cefetamet pivoxil showed good activity in experimental infections in the mouse and rat, suggesting satisfactory bioavailability in these animals after oral administration.