First Reported Case of Actinomyces oris Endocarditis and Bacteremia in the United States: A Case Report.

Introduction: Actinomyces are Gram-positive bacilli found as normal flora in the oral, urogenital, and gastrointestinal tracts. Actinomyces causing endocarditis is extremely rare, with only one prior case of Actinomyces oris endocarditis reported in 2020 in Thailand. We present the first case ever reported in the United States.

Case description: We present a 58-year-old African American woman with multiple comorbidities, including end-stage renal disease, on hemodialysis who presented with altered mentation. On investigations, she had A. oris bacteremia, with echocardiography revealing mitral valve vegetation. She was treated with IV antibiotics followed by oral amoxicillin-clavulanic acid.

Discussion: Our case highlights the diagnostic challenges posed by slow-growing organisms like A. oris in patients with comorbidities, especially on hemodialysis. Blood cultures and transesophageal echocardiography were critical in diagnosing this case. Advanced microbial diagnostic techniques are crucial in identifying the pathogen and the pathogen's susceptibility-guided treatment. This case highlights the importance of early recognition and tailored therapy for rare pathogens like A. oris.