[Multicenter study of the antibacterial activity of a new cephalosporin: CM 40874]

Minimal inhibitory concentrations (MIC) of CM were evaluated on 2 548 bacterial strains isolated in 8 hospitals. CM demonstrated high activity on Enterobacteriaceae, the MIC being less than or equal to 0.125 micrograms/ml for 71% of the 1 362 strains tested, less than or equal to 1 for 99.6%, and less than or equal to 4 for 99.9%. Mode MIC varies little among the different groups of Enterobacteriaceae (from 0.06 to 0.12 micrograms/ml), with the exception of Serratia sp. (mode MIC : 0.25) and Klebsiella oxytoca (mode MIC : 0.03). Most of Enterobacter, Serratia, and Citrobacter sp. strains not inhibited by cefotaxime are readily inhibited by CM at the same concentrations than susceptible strains. CM has less activity on P. aeruginosa (MIC 2-32 micrograms/ml) and Acinetobacter sp. (MIC 8-128). Staphylococci (MIC 32) and Enterococci are not susceptible. Variable activity is found against other Streptococci. CM inhibits Haemophilus sp. at MICs of 0.12 to 0.5 micrograms/ml and Gonococci at MICs of 0.03 to 0.5 (whether the strains produce beta-lactamase or not). Meningococci have a mode MIC of 0.03 micrograms/ml (range 0.008 to 0.25). Thus, CM 40874 is a new third generation cephalosporin with high activity on Enterobacteriaceae, including those strains not susceptible to cefotaxime and good activity on Haemophilus sp. and Neisseria sp. This additional activity is probably supported by enhanced resistance to enzymatic inactivation by beta-lactamases.