Culture-negative polymicrobial chronic Q fever prosthetic valve infective endocarditis utilising 16s rRNA PCR on explanted valvular tissue.

Coxiella burnetti is the causative organism of the zoonotic infection Q fever, of which endocarditis is one of the most common manifestations of the chronic form. Polymicrobial endocarditis with Q fever is extremely rare and yet to be described amongst an Australasian cohort. We present the case of a 32-year-old gardener with culture-negative chronic Q fever prosthetic valve endocarditis concomitant with another bacterial pathogen, leading to aortic root abscess formation requiring a Bentall procedure, extracorporeal membrane oxygenation and prolonged antimicrobial therapy, with a fatal outcome. Unique to our case, Q fever was identified early, and the second pathogen only detected on 16s rRNA PCR of explanted valvular tissue. Given the high risk for morbidity, we recommend that screening for Q fever in endemic areas amongst patients with infective endocarditis from other aetiologies be considered. Additionally, this case highlights the role for Q fever vaccination of the at-risk population with underlying valvulopathy. Furthermore, clinicians should be aware of polymicrobial infective endocarditis, and suspicious in patients with atypical clinical features.