Atypical Presentation of Infective Endocarditis: Reactive Arthritis as the First Clinical Clue

The clinical manifestations of infective endocarditis (IE) may be diverse and atypical, frequently mimicking rheumatologic or autoimmune disorders. The diagnosis of <i>Staphylococcus aureus</i> bacteremia may be delayed if early symptoms are nonspecific, despite the significant risk of underlying IE. We report a 29-year-old previously healthy male who presented with a sudden onset of fever, polyarthralgia, bilateral knee effusions, and a widespread erythematous petechial rash. Leukocytosis, thrombocytopenia, transaminitis, and significantly increased inflammatory markers were found during his initial assessment. Blood cultures revealed methicillin-sensitive <i>Staphylococcus aureus</i>, despite transthoracic echocardiography showing no vegetations. IE was later confirmed by transesophageal echocardiography. Following successful percutaneous AngioVac-assisted vegetation extraction (AngioDynamics, Inc., Latham, NY), the patient experienced complete recovery, and heart function returned to baseline. He completed a six-week course of intravenous cefazolin. This case emphasizes the challenges in diagnosing atypical presentations of IE, such as reactive arthritis and leukocytoclastic vasculitis. It highlights the need for early transesophageal imaging and the limits of transthoracic echocardiography. Additionally, it demonstrates the success of AngioVac extraction for a left-sided vegetation in select patients. Consideration of IE should be prompted by atypical manifestations such as rash and sterile inflammatory arthritis, especially when <i>S. aureus</i> bacteremia is present.