Culture-negative endocarditis: "whatever remains, however improbable, must be the truth"; the importance of asking the right questions!

The complicated case of a patient with recurrent culture-negative endocarditis with a history of repeated mitral valve replacement is described. Investigations disqualified common pathology but serology revealed a diagnosis of Q fever endocarditis. The ongoing problematic management of this patient is described, followed by a brief review of the clinical features, investigations and treatment of Q fever.