In vitro activity of cefpirome (HR 810) against enterococci and staphylococci.
The inhibitory activity of cefpirome (HR 810), a new cephalosporin derivative for parenteral use, was tested by agar dilution methods against Enterococcus faecalis (100 strains), Staphylococcus aureus (40 strains) and coagulase-negative staphylococcal species (60 strains) in comparison with other beta-lactam antibiotics. For E. faecalis, the cefpirome minimum inhibitory concentration (MIC) range was 2-128 micrograms/ml, with an MIC50 of 8 micrograms/ml, and an MIC90 of 64 micrograms/ml. The optimal bactericidal activity against strains with MICs of < or = 8 micrograms/ml occurred at 2-4 times the MIC, and the reduction in the initial inoculum was 99.9-99.7% after 24 h incubation at these concentrations. Mec gene-negative staphylococci (both S. aureus and coagulase-negative species) had cefpirome MICs of 0.25-2 micrograms/ml (MIC50 0.5 microgram/ml, MIC90 1 microgram/ml). Mec gene-positive strains had MICs of 0.5-128 micrograms/ml (MIC50 2 micrograms/ml, MIC90 32 micrograms/ml). Strains with borderline resistance to oxacillin which did not harbor the mec gene and which were susceptible to cefpirome maintained their susceptibility even when high-density inocula were used and after several passages in media containing the antibiotic. These studies present some potential advantages of cefpirome over other cephalosporins in the inhibitory activity against Gram-positive cocci.
Piacentini
E
E
Institute of Microbiology, University of Verona, Italy.
Amalfitano
G
G
Ligozzi
M
M
Canepari
P
P
Fontana
R
R
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002511:Cephalosporins / Q000494:pharmacology*; D013293:Enterococcus faecalis / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D013045:Species Specificity; D013210:Staphylococcus / Q000187:drug effects*; D014640:Vancomycin / Q000494:pharmacology; D000097572:Cefpirome
D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D014640:Vancomycin; D000097572:Cefpirome