In vitro activity evaluations of cefdinir (FK482, CI-983, and PD134393): A novel orally administered cephalosporin

Abstract

Cefdinir, a so-called third-generation oral cephalosporin was tested in vitro against over 700 pathogens from patients with bacteremia. Cefdinir was very active against the Enterobacteriaceae with a 50% minimum inhibitory concentration (MIC 50) value range of ⩽0.03–8 μg/ml. The enteric species having the highest MIC 90s (⩾16 μg/ml) were Citrobacter freundii, and the enterobacters, Morganella morganii, Proteus vulgaris, and Serratia marcescens . Cefdinir was generally two- to fourfold less active than cefixime, but markedly more potent with a wider spectrum compared with older oral cephalosporins, cefaclor or cefuroxime. In contrast to cefixime, cefdinir inhibited Staphylococcus aureus (MIC 90, 1 μg/ml) and other staphylococci. Pneumococci, β-hemolytic streptococci, Haemophilus influenzae, Moraxella catarrhalis, and pathogenic Neisseria spp. (MIC 90s, 0.12–0.5 μg/ml) were cefdinir susceptible, but Pseudomonas aeruginosa, oxacillin-resistant staphylococci and Bacteroides fragilis gr. strains were resistant. Cefdinir was generally bactericidal with a minimal inoculum effect at 10 6 colony-forming units per spot. Cefdinir β-lactamase hydrolysis by some recently described extended broad spectrum β-lactamases was suspected. Cefdinir exhibited a wide, balanced spectrum for an oral cephalosporin indicating possible clinical use against susceptible pathogens in respiratory tract, urinary tract, genital and cutaneous infections.