Antibiotic treatment of infective endocarditis.

At least 85% of patients with infective endocarditis can be cured with effective therapy. Streptococci or staphylococci cause 75% of cases of endocarditis. Patients with penicillin-sensitive viridans or nonenterococcal group D streptococcal endocarditis may be treated successfully with aqueous penicillin G alone for four weeks or with combined penicillin and streptomycin for two weeks. Enterococcal endocarditis should be treated for four to six weeks with a combination of aqueous penicillin G together with either streptomycin or gentamicin. Patients with endocarditis caused by Staphylococcus aureus should receive antimicrobial therapy for four to six weeks with a semisynthetic penicillin (nafcillin or oxacillin) or a cephalosporin such as cephalothin or cefazolin. In urgent cases where empiric antimicrobial therapy is necessary before the causative organism is identified, a combination of aqueous penicillin G, nafcillin, and gentamicin is effective therapy.