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 in situ was referred after an incidental echocardiographic abnormality was detected. He described several years of non-specific fatigue but no typical symptoms of infective endocarditis, and multiple sets of blood cultures were negative. Imaging revealed severe paravalvular regurgitation and dehiscence of the prosthetic valve, prompting surgical intervention. Cultures of the excised aortic valve were negative, but molecular testing identified Coxiella burnetii, and subsequent serology confirmed chronic Q fever. In view of his frailty and a pacemaker which could not be safely explanted, he was managed conservatively with prolonged doxycycline and hydroxychloroquine therapy and close radiological and serological follow-up.  Conclusion: This case illustrates how Coxiella burnetii prosthetic valve endocarditis may present with non-specific symptoms and only be diagnosed with molecular and serological testing. It highlights the importance of considering Coxiella burnetii in culture-negative prosthetic valve endocarditis, even with unclear zoonotic exposure. It also underscores the importance of multidisciplinary decision-making when cardiac device extraction is high-risk. The case also emphasises the infection-prevention implications of unrecognised Coxiella burnetii infection at the time of cardiac surgery, reinforcing the importance of advanced peri-operative planning.