Sch 34343 activity against streptococci and beta-lactam-resistant Enterobacteriaceae.

The in-vitro activity of Sch 34343 was compared with that of cefotaxime, ceftazidime, latamoxef (moxalactam), aztreonam and ampicillin. Against pneumococci, Sch 34343 was as active as ampicillin, whereas against the other streptococci it was less active than ampicillin but significantly better than the other antibiotics against enterococci. With clinical isolates of Enterobacteriaceae resistant to cefotaxime, Sch 34343 had MICs generally less than 2 mg/l. After introduction of plasmid-mediated beta-lactamases into Escherichia coli Cla. there were no significant changes in the MICs of Sch 34343. Mutants of Enterobacter cloacae, Citrobacter freundii and Morganella morganii with derepressed cephalosporinases had susceptibilities equal to or less than 1 mg/l, which were generally lower than those of the other compounds tested. Comparison of parental strains and permeability mutants of E. coli, Ent. cloacae, and Serratia marcescens showed that the increase in MICs of Sch 34343 were lower than those found for the other antibiotics.