Q fever endocarditis in a patient with bioprosthetic heart valves

Q fever endocarditis, caused by Coxiella burnetii, is an uncommon disease that can be difficult to diagnose and often lead to significant morbidity and mortality. We describe a case of a 73-year-old woman with bioprosthetic aortic and mitral valves, who presented with nonspecific symptoms, negative blood cultures, and an unremarkable transthoracic echocardiogram. She was subsequently diagnosed with vasculitis. However, after several months with no improvement with steroid therapy, she was reevaluated and diagnosed with Q fever endocarditis by a positive serology for C. burnetii, along with transesophageal echocardiography, which demonstrated vegetations. In conclusion, this case highlights that Q fever is usually a form of culture-negative endocarditis that should be suspected on the differential diagnosis for patients, especially those with a history of exposure to farm animals and presence of prosthetic valves.