A Case Report: Mitral Valve Infective Endocarditis due to Streptococcus mitis With Cardioembolic Stroke in the Setting of a Neuroendocrine Tumor.

Infective endocarditis is a life-threatening infection of the endocardial surface, most commonly resulting from bacteremia originating from the oral cavity or intravascular sources. However, in some cases, the source of bacteremia remains unidentified, and the role of gastrointestinal pathology is not well defined. We report a patient in her 70s with multiple comorbidities, including mitral annular calcification, who presented with fever, altered mental status, and abdominal pain. Blood cultures grew Streptococcus mitis. Transthoracic and transesophageal echocardiography demonstrated a mobile vegetation on the mitral valve consistent with infective endocarditis. Brain magnetic resonance imaging revealed multiple acute cardioembolic infarctions. During hospitalization, persistent abdominal symptoms prompted further evaluation, which identified severe fecal impaction and a previously undiagnosed ileal neuroendocrine tumor with hepatic lesions. No recent dental procedures or other clear sources of bacteremia were identified. This case raises the possibility that gastrointestinal pathology, including bowel dysfunction and malignancy, may contribute to bacteremia and subsequent infective endocarditis. In patients without an identifiable source, targeted gastrointestinal evaluation may be considered, although further studies are needed to clarify this relationship.