Q fever endocarditis: relapse five years after successful valve replacement for a first unrecognized episode.

A 59-yr-old man presented with mitral endocarditis and negative blood cultures. Antibodies to phase 2 and phase 1 antigens of Coxiella burneti were detected and a diagnosis of Q fever endocarditis was made. Five years earlier, this patient had been successfully treated by aortic valve replacement for a first episode of endocarditis with negative blood cultures. Giemsa and Machiavello stains of the native aortic valve were made retrospectively and showed coccobacilli highly suggestive of Coxiella organisms. It is concluded that the first episode was Q fever endocarditis and that the failure to recognize this aetiology at that time, and the absence of adequate medical therapy, is the cause of the present episode.