Experiences in the management of subacute bacterial endocarditis treated with penicillin

Abstract

Experiences are related in the management of thirty-five patients with subacute bacterial endocarditis treated solely with penicillin on the wards of the Johns Hopkins Hospital. Attention is called to the difficulty of establishing a clinical diagnosis at an early stage of the disease due to the nonspecific or misleading character of the presenting symptoms, the frequent absence of classical physical findings and the prevalence of the infection in individuals with only a minimal degree of cardiac disease. The importance of early diagnosis and institution of treatment is emphasized, as continuation of infection may result in irreparable damage to the heart or kidneys or allow the occurrence of fatal emboli, although in several instances a successful therapeutic result was achieved despite a long lapse of time from the onset of disease until commencement of therapy. It is suggested that any patient with a cardiac murmur and a persistent fever should be suspected of having bacterial endocarditis until careful bacteriologic studies and clinical observations have proved otherwise. The necessity of retaining, both aerobically and anaerobically, all blood cultures for a period of not less than three weeks before they are considered sterile is emphasized as is the importance of searching for unusual organisms such as the genus Bacteroides. The course of these patients during treatment is described and the complications encountered are analyzed relative to adequacy or inadequacy of treatment received. The conclusion is reached that the two major causes of death were the underlying cardiac disease and the persistence of bacterial endocarditis. Hence, the major therapeutic concern is that adequate penicillin be given for an adequate period of time and prior to the development of unalterable cardiac abnormalities. The fact that evidence of active bacterial endocarditis was found upon autopsy examination of three patients who died while receiving treatment commonly regarded as adequate has led to critical appraisal of present criteria of therapeutic adequacy. A plan of therapeutic management is described which is thought to assure adequate therapy for the maximum number of patients. In it the penicillin dosage is based primarily upon clinical evidence of satisfactory response. Such factors as the penicillin sensitivity of bacteria, penicillin blood levels and sterilization of blood cultures have been found to have only limited value. The necessity of continuing treatment for an adequate period of time is discussed and the recommendation is made that 100,000 units of penicillin given intramuscularly every two hours for eight weeks be considered the basic and minimal treatment schedule. The pros and cons of initiating treatment before a bacteriologic diagnosis is completed are stated with the conclusion that a reasonable period of delay is justified provided the condition of the patient does not contraindicate such treatment. It is advised that blood cultures be obtained before antibiotic therapy is given to any patient with valvular or congenital heart disease who has a localized bacterial infection, lest a latent bacterial endocarditis be obscured. The value of prolonged convalescence to allow maximal healing of damaged valves is indicated. Consideration is given to the need for adequate prophylaxis against the development of subacute bacterial endocarditis not only during dental extractions but during any type of procedure which might result in transient bacteremia. The elimination of foci of infection which might serve as a reservoir of infection or reinfection is recommended. In conclusion, the immediate results of treatment are discussed and the course of surviving patients over a three to thirty-six months' period is described. An evaluation is attempted of the influence upon the ultimate outcome of certain factors, including the presence of cardiac failure before, during and after the onset of bacterial endocarditis. The final determinants of failure or success in the treatment of subacute bacterial endocarditis with penicillin appear to be the degree of cardiac damage resulting either from the bacterial infection or an underlying disease process, the severity of the embolic occurrences and the resistance of the infecting organisms.