Case Report: Infective Endocarditis of Mechanical Aortic Valve Due to Neisseria elongata Bacteremia

BACKGROUND Neisseria elongata is a infrequent cause of infective endocarditis (IE). Although considered a commensal bacterium of the human nasopharynx, N. elongata has been shown to be the cause of significant disease in humans, namely endocarditis, osteomyelitis, and septicemia. CASE REPORT We report the case of a 53-year-old man with a past medical history of mechanical aortic valve who presented to the hospital for evaluation of eleven days of recurrent and relapsing fevers and was admitted for severe sepsis with concern for endocarditis. Blood cultures revealed N. elongata bacteremia, and an echocardiogram did not show any vegetations, although it was limited by mechanical aortic valve shadowing. The patient recovered after six weeks of treatment with intravenous ceftriaxone and oral ciprofloxacin. CONCLUSIONS Clinicians should be aware of the possibility of the previously considered non-pathogenic N. elongata as a source of IE caused by gram-negative organisms, as it can potentially cause severe disease and multiple complications. Our case additionally highlights that IE has highly variable clinical presentations. Thus, it is essential to utilize the Duke criteria as only a clinical guide for the diagnosis of IE rather than a substitute for clinical judgment and the decision to treat a patient with suspected IE.