Diagnosis of Prosthetic Endocarditis Caused by Coxiella burnetii Using PET Scan and PCR: A Case Report of Chronic Q Fever.

Chronic blood culture-negative endocarditis (BCNE) presents a significant challenge for early diagnosis and treatment, leading to increased morbidity and mortality. This report presents a 30-year-old man with a history of BCNE who presented with an intermittent fever lasting 3 months. His medical history was complex and characterized by tetralogy of Fallot (TOF), multiple cardiac surgeries, and previous positive pathological results for infection and endocarditis. A PET/CT scan revealed hypermetabolic lesions near the prosthetic valves and aortic grafts, prompting further investigation for potential causative organisms. Subsequent serological testing and PCR confirmed the presence of Coxiella burnetii, leading to a diagnosis of Q fever endocarditis. Treatment with doxycycline and hydroxychloroquine initiated significant improvement. Follow-up after 3 months showed that the patient remained stable with significant improvements in serological tests and imaging. This case underscores the necessity of considering atypical pathogens like C. burnetii in patients with BCNE and chronic endocarditis, particularly those with complicated cardiac histories.