Rare case of bacteremia, liver abscess and possible infective endocarditis caused by Fusobacterium nucleatum

Fusobacterium nucleatum is a Gram-negative obligate anaerobic bacterium typically found as a commensal in the human oral cavity, gastrointestinal and female genital tract. While it is a common cause of endodontic infections, it is a rare cause of infective endocarditis (IE), which can lead to high morbidity if diagnosis is delayed due to the challenges of culturing anaerobic bacteria. The case of a 75-year-old male patient with a history of type 2 diabetes who presented with high fever, rigors, and hemodynamic instability is presented herein. Physical examination revealed a new systolic murmur. Initial investigations identified inflammatory syndrome and elevated liver enzymes. Further imaging via contrast-enhanced ultrasound and computed tomography confirmed two abscesses in the left lobe of the liver. Blood cultures grew F. nucleatum, and a transesophageal echocardiogram demonstrated vegetation on the aortic valve. The patient met the Modified Duke criteria for a diagnosis of infective endocarditis. It was later elicited that the patient had undergone dental interventions one month prior to admission. The patient was successfully treated with a six-week course of targeted antimicrobial therapy consisting of ceftriaxone and metronidazole, resulting in favorable clinical recovery. Fusobacterium species are rare but significant causes of invasive infections such as liver abscesses and IE. This case emphasizes that anaerobic pathogens should be suspected in patients presenting with unexplained sepsis, concomitant deep-seated abscesses, or a history of recent dental procedures. Early use of echocardiography and anaerobic blood cultures are essential for the timely diagnosis of these rare clinical entities.