In vitro activity of cefodizime

Cefodizime is a bactericidal cephem with the typical broad spectrum activity of an aminothiazolyl cephalosporin, including both gram-positive and gram-negative bacteria: its MIC90 is 0.125 mg/l for Streptococcus pneumoniae, Streptococcus pyogenes and other streptococci; and 0.05 mg/l for Haemophilus spp., Neisseria meningitidis, Neisseria gonorrhoeae and Moraxella catarrhalis; while beta-lactamase positive strains of M. catarrhalis require 1 mg/l. Less than 1 mg/l is needed for Escherichia coli, Klebsiella spp., Proteus spp. and Shigella spp. The MIC90 is 4 mg/l for methicillin-sensitive Staphylococcus aureus, Morganella morganii, Providencia spp. and most strains of Serratia marcescens, Citrobacter spp. and Enterobacter spp. Staphylococcus epidermidis, Enterococcus faecalis and most strains of Pseudomonas spp. and Acinetobacter spp. are considered cefodizime-resistant. Cefodizime is unaffected by plasmid-mediated beta-lactamases, but it is hydrolyzed by some chromosomally mediated enzymes, thus resembling other third-generation cephalosporins. Cefodizime has high affinity for PBP 3 and PBP IA and IB (Escherichia coli); in S. aureus it shows the highest affinity for PBP 1.