Laboratory evaluation of ceftizoxime, a new parenteral cephalosporin.

(6,7R)-7-[(Z)-2-(2-Amino-4-thiazoyl)-2-methoxyiminoacetamido]-8-oxo-5-thia-1 -azabicyclo[4,2,0]oct-2-ene-2-carboxylate (ceftizoxime), a new parenteral cephalosporin, in more potently active in vitro and in vivo against various gram-negative bacilli including the opportunistic pathogens such as Enterobacter, Citrobacter species and Serratia marcescens than cephalosporins and cephamycins recently developed. Ceftizoxime is extremely stable to various types of beta-lactamases, and has a high ability to penetrate the outer membrane of gram-negative organisms.