Diagnosis of Prosthetic Endocarditis Caused by <scp> <i>Coxiella burnetii</i> </scp> Using <scp>PET</scp> Scan and <scp>PCR</scp> : 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 <i>Coxiella burnetii</i>, 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 <i>C. burnetii</i> in patients with BCNE and chronic endocarditis, particularly those with complicated cardiac histories.