Subacute bacterial endocarditis of undetermined etiology

Of A current series of 166 patients with subacute bacterial endocarditis, we have encountered eleven (7 per cent) with consistently sterile blood cultures despite recourse to anaerobic methods, enriched mediums, arterial punctures, and cultures taken after the administration of epinephrine. ∗ ∗ Epinephrine technique for obtaining positive blood cultures was originally suggested by Dr. Myron Prinzmetal and Dr. B. S. Oppenheimer. The diagnosis in two of our patients was confirmed by necropsy findings. In the remainder, the recognition of the presence of the syndrome was dependent upon the classical manifestations of protracted fever, valvulitis, embolic phenomena, and usually a splenomegaly. Needless to say, the other possible etiological factors in a prolonged pyrexia were excluded by extensive laboratory investigations. This communication has for its purpose a summation of eleven histories, a report of the responses to therapy, and the suggestion that the response to treatment with anti-infective agents be employed in the future as a therapeutic test.