AN IN-VITRO CHARACTERIZATION OF CEFDITOREN, A NEW ORAL CEPHALOSPORIN

Cefditoren (ME 1206) is a new cephalosporin available for oral adminis tration as the pivaloyloxymethyl ester (ME 1207). The effect of medium formulation. pH, cation concentration and inoculum on the in vitro ac tivity of cefditoren was investigated prior to determining its compara tive antibacterial potency against a wide range of clinical bacterial isolates, its bactericidal activity against susceptible strains and th e duration of its post-antibiotic effect (PAE). Cefditoren was shown t o possess a broad-spectrum of cidal antibacterial activity against bot h Gram-positive and Gram-negative species with stability to many beta- lactamases of clinical importance. Its activity against Gram-positive species was similar to augmentin and cefuroxime, but superior to that of cefaclor and cefixime, while its beta-lactamase stability was simil ar to that of cefixime and ceftazidine, characterizing it as a third g eneration cephalosporin. Investigation of the effect of laboratory var iables on the in vitro activity of cefditoren indicates that it will p resent no special problems when tested in the clinical setting against bacterial pathogens. PAE of 0.9 h, or greater, for Staphylococcus spp , Streptococcus pneumoniae and Moraxella catarrhalis may support the u se of an extended dose-interval when cefditoren is used for the treatm ent of respiratory tract infections.