Chronic Q fever prosthetic valve endocarditis with a retained pacemaker: multidisciplinary and infection prevention considerations

Introduction: Chronic Q fever, caused by Coxiella burnetii, is an important cause of culture-negative infective endocarditis, particularly in patients with congenital valvular disease or prosthetic valves. Clinical presentation is often insidious, and diagnosis is challenging, relying predominantly on serology and molecular diagnostics. Case presentation: A man in his 60s with a bioprosthetic aortic valve for prior bicuspid aortic valve disease and a permanent pacemaker was referred after an incidental echocardiographic abnormality. He reported several years of non-specific symptoms but was afebrile at presentation, and multiple blood cultures yielded no clinically significant pathogen. Imaging demonstrated severe paravalvular regurgitation and dehiscence of the prosthetic aortic valve, prompting redo aortic valve and aortic root replacement. Cultures of the excised valve remained negative, while broad-range 16S rRNA polymerase chain reaction identified C. burnetii. Serology supported a diagnosis of Q fever endocarditis, with a phase I IgG titre of 1:10,240. Following diagnosis, the specialist Q fever multidisciplinary team (MDT) recommended pacemaker retention following a risk-benefit assessment, alongside 24 months of doxycycline and hydroxychloroquine, with a minimum of 18 months. At four-month follow-up, antibody titres remained unchanged, while C-reactive protein had normalised. Conclusion: This case illustrates the difficulty of diagnosing C. burnetii prosthetic valve endocarditis in the absence of classical clinical features. The postoperative diagnosis also raised challenges regarding pacemaker retention and potential occupational exposure during surgery, emphasising the importance of detailed occupational history-taking and early consideration of Q fever in culture-negative endocarditis.