Structure-activity relationships within a series of C(7)-substitutedoxyiminocephalosporins containing the C(3)-methylaminopyridiniumthiomethyl substituent : synthesis and biological properties of BRL 57342 and some close analogues

(6R,7R)-7-[2-(2-Amino-4-thiazolyl)-2-[(Z)-[(S)-carboxy(3,4- dihydroxyphenyl)methyl]oxyimino]acetamido]-3-(1-methylaminopyri dinium-4-thiomethyl)ceph-3-em-4-carboxylate sodium salt (BRL 57342, 1f) combines excellent in vitro antibacterial potency against Gram-positive and Gram-negative bacteria, including P. aeruginosa and Acinetobacter spp., with excellent stability to extended spectrum beta-lactamases. This potency is reflected in in vivo efficacy studies.