0521779407-10 CUNY1086/Karliner 0 521 77940 7 June 7, 2007 18:40
Infective Endocarditis 831■Surgical intervention indicated if heart failure fails to respond to
medical management, if blood cultures remain positive 7–10 days
despite appropriate antibiotic therapy, in fungal endocarditis, in
many cases of Gram-negative endocarditis, myocardial or valve ring
abscesses and if recurrent embolic events occurspecific therapy
■Empirical therapy while awaiting the results of cultures directed
against streptococci, enterococci and S. aureus – nafcillin or oxacillin
plus penicillin or ampicillin plus gentamicin; in the penicillin-
allergic patient, vancomycin used instead of the penicillins
■Viridans streptococci – for susceptible strains (minimum inhibitory
concentration or MIC≤0.1 micrograms/mL) penicillin or ceftriax-
one or vancomycin (in penicillin allergic patient) for 4 weeks; dura-
tion of therapy shortened to 2 weeks if gentamicin added to the peni-
cillin regimen; 2-week regimen not indicated if symptoms present for
greater than 3 months, if complications present, in renal failure or the
elderly; prosthetic valve endocarditis treated 6 weeks with penicillin
and 2 weeks with gentamicin; if MIC >0.1 micrograms/mL and≤0.5
micrograms/mL, penicillin for 4 weeks and gentamicin for the first
2 weeks; in the penicillin-allergic patient, vancomycin for 4 weeks;
for nutritionally variant streptococci and viridans streptococci with
MIC’s >0.5 micrograms/mL, therapy as for enterococci
■Enterococci – penicillin or ampicillin or vancomycin (in the
penicillin-allergic patient) plus gentamicin for 4–6 weeks (6 weeks for
prosthetic valves and if symptoms >3 months); no established reg-
imens if high-level resistance to aminoglycosides (MIC >500–2000
micrograms/mL), but 8–12 weeks of intermittent or continuous infu-
sion of high-dose penicillin or ampicillin may be curative in 50%;
surgery may be only other therapeutic option
■Staphylococci – for methicillin-susceptible strains, nafcillin or
oxacillin or cefazolin (in the penicillin-allergic patient without IgE
hypersensitivity) for 4–6 weeks; addition of gentamicin for 3–5
days shortens duration of bacteremia; in patients with anaphy-
laxis to penicillin with methicillin-sensitive S. aureus, or those with
methicillin-resistant strains, only therapy is vancomycin for 4–6
weeks; tricuspid valve endocarditis in IV drug users can be treated
for 2 weeks if gentamicin and anti-staphylococcal drug used in
combination; coagulase-negative staphylococci usually cause pros-
thetic valve endocarditis and are treated with vancomycin plus
rifampin for 6 weeks plus gentamicin for the first 2 weeks