Bacterial Endocarditis and Prosthetic Valves

Bacterial Endocarditis and Prosthetic ValvesA MONG the major challenges to the physician and surgeon managing patients with valvular heart disease by the use of prosthetic valves is the possibility of postoperative bacterial endocarditis.Such infections occur in relation to the seat of the prosthesis and may occur either in early or late postoperative states.The challenges include both the phases of prevention and treatment.In the area of prevention, one problem is that prophylactic antibiotic therapy does not necessarily prevent the occurrence of infection.1 2 One reason is that among the organisms involved certain are resistant to the effects of the common prophylactic antibiotic programs employed.The organisms that have proved particularly troublesome are those in the category of penicillin-resistant Staphylococcus3 and various gram-negative organisms.4Another reason is that organisms which are sensitive to the prophylactic antibiotics may survive at the opera- tive site.Assuming that one may come up with an antibiotic program appropriate to deal both with sensitive and resistant organisms, the evidence suggests that it is difficult to obtain sufficiently high concentrations of antibotics for destruction of organisms in relation to sutures and in the tissues bordering on the seat of the prosthesis.These difficulties underlie an escape phenomenon in which organisms inadvertently inserted at operation lie dormant during the early postoperative period and later, weeks or months postoperatively, bloom so as to cause an evident and significant infection.2 4 Assuming that certain late infections in relation to prosthetic valves represent infection some time after the operation, one must be aware of the various portals of entry of organisms to which the patient is subject.-6Respiratory or dental infections and infections relating to inserted intravenous needles or catheters are sources of bacterial endocarditis.