A new aminothiazolylcephalosporin having 1-carboxyethoxyimino group, ME1228.

Aminothiazolylacetamidocephalosporins having 1-carboxyethoxyimino groups were synthesized and found to have excellent antibacterial activities including anti-pseudomonal activity and low toxicities. Among these cephalosporins, ME1228 having (S)-1-carboxyethoxyimino substituent and being combined with an (N-ethyl-4-pyridinio)thiomethyl group at C-3 showed marked therapeutic effects against systemic infections in mice and was selected as the best candidate for further evaluation.