CEPHALOTHIN-GENTAMICIN SYNERGISM IN EXPERIMENTAL ENTEROCOCCAL ENDOCARDITIS

Previously, others suggested that the in vivo failure of cephalothin plus an aminoglycoside to cure enterococcal endocarditis could be overcome, if the peak serum cephalothin level exceeded the MIC of the enterococcus by several fold. Therefore, rabbits with enterococcal endocarditis were treated with gentamicin and either penicillin or cephalothin at doses providing peak serum levels about 5 and 10 times the MIC of the enterococcus. Of these regimens, only cephalothin at doses providing peak levels 10 times the MIC of the enterococcus resulted in high valve sterilization (100%) and survival rates (90%). Cephalothin and gentamicin should not be used to treat human enterococcal endocarditis, because the dose of cephalothin required for cure would appear to be prohibitively high. © 1978 The British Society for Antimicrobial Chemotherapy.