Blood culture negative cardiovascular infection in a patient with multiple sclerosis

: A patient with multiple sclerosis presented with seronegative C. burnetii endocarditis diagnosed using C. burnetii-specific polymerase chain reaction and fluorescence in situ hybridization on cardiovascular biopsy. This case supports the necessity of a systematic polymerase chain reaction testing of removed cardiac valves because blood culture-negative endocarditis can be pauci-symptomatic, and serological tests can be negative in cases of immunosuppression.