Coxiella burnetii Endocarditis in a Patient with Systemic Lupus Erythematosus: A Case Report of a Diagnostic Challenge.

BACKGROUND There is a close association between Q fever and autoimmune disease, with some case reports in the literature of Q fever presenting as systemic lupus erythematosus (SLE) and others documenting their coexistence. However, making the correct diagnosis remains challenging and Q fever often is overlooked. Therefore, it is essential to review such a rare presentation to help in accurate diagnosis in future cases. This report is of a case of endocarditis due to Coxiella burnetii in a patient with Q fever and a history of SLE. CASE REPORT We report the case of a 43-year-old man with a history of SLE and rheumatic heart disease, status post-valve replacement. The patient initially presented with an acute kidney injury in the setting of a history of full-house lupus membranous nephropathy, which was diagnosed on kidney biopsy. The patient had been on immunosuppressive therapy for 2 years. Shortly after he was admitted, echocardiography was ordered because the patient had progressive dyspnea, revealing infective endocarditis involving multiple valves. He underwent valve repair surgery and was placed on an extended course of antibiotic therapy. His symptoms gradually resolved, with normalization of his immunological markers. The patient's immunosuppressive regimen was eventually discontinued. He remains on lifelong antibiotic suppression therapy. CONCLUSIONS This case highlights the importance of awareness of infectious causes of endocarditis in patients with underlying autoimmune diseases such as SLE. This rare case of C burnetii endocarditis may have been associated with underlying valvular SLE.