Prosthetic valves have been used extensively for severe cardiac valvular dysfunction for the past 3 decades. Prosthetic cardiac valves may be infected with organisms causing
bacteremia, particularly gram-positive cocci. Staphylococcus epidermidis (
coagulase negative staphylococci) and Staphylococcus aureus , both
methicillin-susceptible S. aureus and methicillin-resistant S. aureus (MRSA) strains, are the most frequent pathogens causing prosthetic valve
endocarditis (PVE).
Vancomycin has been the cornerstone of
therapy for serious MRSA
infections including
bacteremia and
endocarditis. Clinicians have noted that MRSA
bacteremias treated with
vancomycin often fail to clear even with prolonged
therapy. Persistent or prolonged MRSA
bacteremia unresponsive to
vancomycin therapy has led to the treatment of these
infections by other agents, that is,
quinupristin, dalfopristin,
linezolid, or
daptomycin. These
antibiotics have been found particularly useful in treating MRSA
bacteremias unresponsive to
vancomycin therapy. We report a case of a patient who presented with MRSA PVE complicated by perivalvular aortic
abscess with persistent MRSA
bacteremia unresponsive to
vancomycin therapy. The patient's MRSA
bacteremia was cleared with
daptomycin therapy (6 mg/kg/d). Because the patient refused surgery,
daptomycin therapy was continued in hopes of curing the
endocarditis and sterilizing the perivalvular aortic
abscess. Transesophageal echocardiogram revealed a decrease in
abscess in the aortic perivalvular
abscess after 1 week of
daptomycin therapy. The patient made an uneventful recovery. The cure of PVE and perivalvular
abscesses usually requires removal of the prosthetic device and
abscess drainage. In this case, in which surgery was not an option, medical
therapy of PVE and a decrease in size of the aortic perivalvular
abscess were accomplished with
daptomycin therapy.
Daptomycin is an alternative to
vancomycin therapy in patients with prolonged or persistent MRSA
bacteremia secondary to
endocarditis or
abscess.