Antimicrobial prophylaxis of experimental endocarditis caused by Staphylococcus epidermidis.
Using two different strains of Staphylococcus epidermidis in a rat model of experimental endocarditis, we examined the prophylactic efficacy of cefamandole (200 mg/kg/dose), cefazolin (200 mg/kg/dose), nafcillin (200 mg/kg/dose), and vancomycin (20 mg/kg/dose). In vitro susceptibility testing demonstrated that both test strains were resistant to methicillin and cefazolin and susceptible to cefamandole and vancomycin. A 10(6) cfu inoculum was used for both strains, an inoculum which produced endocardial infections in greater than 90% of rats. Initial doses of each antibiotic were given 45 min to 1 h prior to bacterial challenge and were followed by six additional doses of each antibiotic administered subcutaneously every 6 h. The efficacy rates of cefamandole (84.0%) and cefazolin (70.8%) were exactly the same for rats infected with either S. epidermidis strain. Similar efficacy rates were seen in rats infected with either strain and treated with vancomycin (94.4% and 86.7%). Unlike the other three drugs, the efficacy of nafcillin was quite different in rats challenged with the two strains (62.5% and 38.5%, p = 0.19). It appears that cefamandole and cefazolin may have considerable prophylactic efficacy against certain infecting strains of methicillin-resistant, coagulase-negative staphylococci when relatively large doses of cephalosporins are administered subcutaneously in this animal model.
Baddour
L M
LM
Department of Medicine, University of Tennessee, Memphis.
Hill
M M
MM
Felty-Duckworth
A M
AM
D000818:Animals; D002511:Cephalosporins / Q000493:pharmacokinetics / Q000627:therapeutic use*; D004195:Disease Models, Animal; D004697:Endocarditis, Bacterial / Q000188:drug therapy* / Q000382:microbiology / Q000517:prevention & control; D008826:Microbial Sensitivity Tests; D009254:Nafcillin / Q000493:pharmacokinetics / Q000627:therapeutic use; D011292:Premedication; D051381:Rats; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000382:microbiology / Q000517:prevention & control; D013212:Staphylococcus epidermidis; D014640:Vancomycin / Q000493:pharmacokinetics / Q000627:therapeutic use
D002511:Cephalosporins; D009254:Nafcillin; D014640:Vancomycin