In vitro activity of Ro 23-9424, ceftazidime, and eight other newer beta-lactams against 100 gram-positive blood culture isolates.

One hundred Gram-positive bacteremia organisms from five important genus groups were tested against 10 newer beta-lactams. Ceftazidime was significantly less active (50% of strains at less than or equal to 8 micrograms/ml) compared to other cephalosporins. The penems (FCE-22101 and HRE-664) and imipenem were each superior to the cephalosporins with 92-93% inhibition of strains. A novel fused co-drug of fleroxacin and desacetyl-cefotaxime, Ro 23-9424, was 100% effective against these Gram-positive pathogens at less than or equal to 8 micrograms/ml. Several of these compounds should receive consideration for clinical trials for empiric therapy among neutropenic patient infections where Gram-positive pathogens may be more prevalent.