Bactericidal activity of cefpirome (HR 810) against 513 gram-negative bacteria isolated from blood of septicemic patients.

The profile of antibacterial activity of cefpirome was compared with that of nine other antimicrobial agents against 513 gram-negative bacteria isolated from septicemic patients. All strains were evaluated for their sensitivity by disc diffusion and broth dilution tests (MIC and MBC). Cefpirome was compared to cefazolin, cefuroxime, ceftazidime, ceftriaxone, aztreonam, imipenem, ticarcillin, tobramycin and ciprofloxacin. Among the five cephalosporins tested in this study, cefpirome was the most active against all isolates. The MIC50 and MIC90 of eight isolates of Acinetobacter calcoaceticus were 2 and 4 mg/l and those of 89 Pseudomonas aeruginosa were 2 and 8 mg/l, respectively. The MIC90 values of cefpirome for all other groups of bacteria were < or = 1 mg/l. The activity of cefpirome against gram-negative bacteria is at least as good as that of aztreonam and imipenem. The only drug showing a better profile of activity than cefpirome is ciprofloxacin. The scattergram of the 513 isolates for cefpirome MICs and inhibitory zones with the 30 micrograms disc, showed that only eight isolates were not susceptible to cefpirome. These data suggest that the in vitro activity of cefpirome is comparable to if not better than that of other beta-lactams and tobramycin.