title: Infective endocarditis caused by Streptococcus bovis resistant to the lethal effect of penicillin G.
abstract: Penicillin G alone is generally recommended for the treatment of infective endocarditis caused by Streptococcus bovis because clinical isolates of S bovis are represented as being uniformly and markedly susceptible to penicillin G. However, two strains of S bovis recovered from two patients with bacterial endocarditis were resistant to the lethal effect of penicillin G. Combination therapy, cefazolin sodium and gentamicin sulfate in patient 1 and penicillin G and gentamicin in patient 2, was necessary; synergy, as manifested by lethal activity against the infecting strains, was demonstrated in the laboratory. We stress the need to determine the minimal lethal concentration of penicillin G for clinical isolates of S bovis. Until such information is available, particularly in life-threatening infections, combination drug therapy, consisting of an aminocyclitol added to a beta-lactam antimicrobic, should be used.
mesh_terms: D002437:Cefazolin / Q000494:pharmacology / Q000627:therapeutic use; D004357:Drug Synergism; D004697:Endocarditis, Bacterial / Q000188:drug therapy* / Q000382:microbiology; D005260:Female; D005839:Gentamicins / Q000494:pharmacology / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008875:Middle Aged; D010400:Penicillin G / Q000494:pharmacology / Q000627:therapeutic use*; D010403:Penicillin Resistance; D013290:Streptococcal Infections / Q000188:drug therapy* / Q000382:microbiology
chemical_list: D005839:Gentamicins; D002437:Cefazolin; D010400:Penicillin G