Unusual Pathogens in Narcotic-Associated Endocarditis

We report the cases of three adults with a history of intravenous drug abuse who developed endocarditis caused by Corynebacterium xerosis, Neisseria subflava, and Neisseria flavescens, respectively. No cases of endocarditis caused by C. xerosis or N. flavescens and only one case caused by N. subflava have previously been reported in association with narcotic addiction. The prominent clinical features in all patients included poor response to antibiotic therapy, persistent fever, and major embolic events. Stigmata of infection with human immunodeficiency virus, as manifested by oral candidiasis, cervical lymphadenopathy, and serologic evidence, were present in two of the three patients. At our institution, where Staphylococcus aureus remains the most frequent etiologic agent of narcotic-associated endocarditis, the occurrence of these three cases in a 9-month period is striking. We speculate that infection with human immunodeficiency virus may play a role in the pathogenesis of endocarditis caused by these unusual organisms.