Prosthetic valve endocarditis

About 2% of patients with a prosthetic valve will develop endocarditis. This may occur within a few weeks of the valve replacement operation (early) or many months or years later (late). The infecting organisms, pathogenicity and prognosis differ in the two groups. The incidence of early prosthetic valve endocarditis (PVE) is under 1%; the predominant organisms are staphylococci that are acquired in the operating theatre or in the intensive therapy unit. Early PVE usually follows wound sepsis that may initially appear trivial. The mortality rate is around 70%, but such infections should be preventable by stringent antisepsis, good surgical technique and (perhaps) perioperative antistaphylococcal antibiotics. The incidence of late PVE is about 1% per annum. The infecting organisms are similar to those causing native valve endocarditis, predominantly streptococci. The commonest source of these organisms is the mouth and regular dental care and appropriate prophylactic antibiotics should help to prevent infection. The mortality rate of late PVE is around 10%. Failure of medical treatment in PVE is an indication for surgery to remove the infected valve(s) and this should not be delayed. The optimum length of treatment for PVE is unknown but it is seldom necessary to give antibiotics for more than 6 weeks except in Coxiella burnetii infection.