INFECTIVE ENDOCARDITIS CAUSED BY HACEK MICROORGANISMS

The HACEK group of fastidious gram-negative organisms is a recognized but unusual cause of infective endocarditis, responsible for approxima tely 3% of cases. We report our experience with 45 cases of endocardit is caused by HACEK organisms. In Olmsted County,Minnesota, the inciden ce of HACEK endocarditis was 0.14 per 100,000 person-years. In patient s with native valves, 33 cases occurred, and in patients with prosthet ic valves, 12 cases occurred. The most common presenting symptoms were fever, splenomegaly, new or changing murmur, and microvascular phenom ena. Symptoms were present in the majority of patients anywhere from t wo weeks to six months prior to diagnosis. Blood cultures became posit ive in a mean of 3.375 days, and therapy with a beta-lactam alone or a s part of a combination was given for anywhere between three and six w eeks. Within the first month of diagnosis, surgery was performed for 1 3 regurgitant valves in 11 patients (24%). Echocardiography was an ins ensitive predictor of subsequent major arterial embolization (odds rat io, 1.33; 95% confidence interval, 0.31-5.67). The overall survival in our cohort of patients was 87%. These results confirm previous report s that HACEK endocarditis portends a favorable prognosis.