Susceptibility of United States clinical trial isolates to cefprozil and cefaclor.
First bacterial isolates (n = 2022) from patients enrolled in the United States cefprozil clinical trials were tested for susceptibility to cefprozil and cefaclor. Cefprozil was two- to eightfold more active than cefaclor against Gram-positive bacteria based on minimum inhibitory concentration (MIC50 and MIC90) values. The differential was greatest, for the most part, for the 80% of isolates of each species with the lowest MICs. Against Gram-negative bacterial species, the two cephalosporins were very similar in activity and MIC90 values ranged from 2 to 8 micrograms/ml for the most prevalent pathogens except Enterobacter spp., which were resistant. The majority of streptococci (98%) were susceptible to < or = 0.5 microgram/ml of cefprozil, and the majority of staphylococci tested (> 90%) were susceptible to < or = 4 micrograms/ml of cefprozil. These results for isolates primarily from community-acquired infections were similar to previously reported results from uncharacterized or hospital-associated isolates.
Kessler
R E
RE
Department of Microbiology, Bristol-Myers Squibb Company, Wallingford, Connecticut 06492.
Fung-Tomc
J C
JC
D002433:Cefaclor / Q000494:pharmacology*; D002511:Cephalosporins / Q000494:pharmacology*; D002986:Clinical Trials as Topic; D004352:Drug Resistance, Microbial; D006094:Gram-Positive Bacteria / Q000187:drug effects*; D006801:Humans; D008826:Microbial Sensitivity Tests; D014481:United States; D000097670:Cefprozil
D002433:Cefaclor; D002511:Cephalosporins; D000097670:Cefprozil