Unusual cause of infective endocarditis in an elderly patient with a rare condition

A 77-year-old woman presented to the emergency department with a 1-week history of anorexia, fatigue, general malaise and a 3-day history of fever. Clinical examination revealed livedo reticularis across the anterior aspect of her knees and a pansystolic murmur. Laboratory evaluation found neutrophil leucocytosis; elevated C reactive protein and blood cultures grew Streptococcus acidominimus. Transthoracic echocardiography displayed vegetation on the mitral valve and a left atrial myxoma. She was treated with intravenous benzylpenicillin and erythromycin for the infective endocarditis (IE) and remains well 3 months post-treatment. S. acidominimus is considered a common veterinary pathogen rarely found in humans. To the best of our knowledge, only two prior reports of IE due to this organism exist in the literature. This case highlights how rare pathogens can cause unusual presentation and the importance of IE as a differential even in the absence of classical signs, if fever and new murmur are present.