In vitro activity of a new semisynthetic cephalosporin: cefoperazone.

Cefoperazone is a new semisynthetic cephalosporin with excellent antibacterial activity. This study included more than 1,500 clinical isolates whose susceptibility to cefoperazone was determined by minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). Cefoperazone was highly active against Enterobacteriaceae including indolepositive Proteus, Serratia and Enterobacter sp. Particularly noteworthy was the high activity of cefoperazone against Pseudomonas and Acinetobacter strains, which are usually resistant to first- and second-generation cephalosporins. The activity of cefoperazone against Staphylococcus aureus, Staphylococcus epidermidis, group D streptococci and Haemophilus was also determined. In general, the differences between MIC and MBC were minimal. Additional studies were carried out to determine the effect of inoculum size on cefoperazone activity.