MEDizzy - A 72-year-old man with a history of hypertension, diabetes

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INFECTIVE ENDOCARDITIS

A 72-year-old man with a history of hypertension, diabetes mellitus, and aortic stenosis returns to your clinic 3 weeks after being diagnosed with a viral upper respiratory infection. Today he complains of continued fever, myalgias, malaise, and night sweats. At the time of the initial presentation, the patient was treated conservatively with acetaminophen and encouraged to maintain oral fluid intake. He denies having rigors, chest pain, dyspnea, cough, diarrhea, or dysuria. The results of physical examination are as follows: temperature, 100.5 degrees F (38 degrees C), blood pressure, 156/87 mm Hg, heart rate, 92 beats per min, respiratory rate, 14 breaths per min, and O2 saturation, 99 percent on room air. The patient is in no acute distress. The lungs are clear to auscultation bilaterally. Heart examination reveals a regular heart rate with a 3 out of 6 systolic ejection murmur that radiates to the carotid arteries bilaterally. There is no skin rash. The neurologic examination is non-focal. You are concerned about the possibility of occult infection or malignancy and admit the patient for workup for fever of undetermined origin (FUO). A transthoracic echocardiogram demonstrates a 6 mm vegetation on the aortic valve. Blood cultures from three sites are obtained. For this patient, which of the following statements about subacute bacterial endocarditis (SBE) is true?

ExplanationThe correct answer is B. The constitutional symptoms of SBE usually begin insidiously and often persist for weeks to months. Fevers, sweats, weakness, myalgias, arthralgias, malaise, anorexia, and easy fatigability are prominent. Fewer than 5 percent of patients are afebrile; such patients are often elderly, markedly malnourished, or azotemic. Fever and other nonspecific symptoms in the presence of a predisposing cardiac lesion may be the only clinical manifestations of SBE in some patients. In most patients with SBE, blood cultures drawn before initiation of antibiotic therapy are positive, reflecting the sustained bacteremia associated with an infected endothelial surface. Factors associated with an increased risk of embolization include vegetations of 10 mm or more in size as seen on echocardiography, vegetations on the mitral valve, particularly the anterior leaflet, vegetations that increase in size during therapy; and infection by Staphylococcus aureus. The incidence of arterial emboli decreases about 10-fold during the initial 2 weeks of antimicrobial therapy.